<PAGE>


    As filed with the Securities and Exchange Commission on August 2, 1999

                                                        Registration No. 333-

================================================================================

                      SECURITIES AND EXCHANGE COMMISSION

                            WASHINGTON, D.C. 20549

                             ____________________

                                   FORM S-8
                            REGISTRATION STATEMENT
                                     Under
                          THE SECURITIES ACT OF 1933

                             ____________________

                       FOCAL COMMUNICATIONS CORPORATION
            (Exact Name of Registrant as Specified in Its Charter)

             Delaware                                36-4167094
     State or Other Jurisdiction                  (I.R.S. Employer
     of Incorporation)                            Identification No.)

                     200 North LaSalle Street, Suite 1100
                            Chicago, Illinois 60601
                   (Address of Principal Executive Offices)

                  1998 Equity and Performance Incentive Plan
                           (Full Title of the Plan)

                             ____________________

                               Joseph A. Beatty
             Executive Vice President and Chief Financial Officer
                       Focal Communications Corporation
                     200 North LaSalle Street, Suite 1100
                            Chicago, Illinois 60601
                    (Name and Address of Agent For Service)

                                (312) 895-8400
         (Telephone Number, including Area Code, of Agent For Service)

                                With a copy to:
                             Elizabeth C. Kitslaar
                          Jones, Day, Reavis & Pogue
                                77 West Wacker
                         Chicago, Illinois 60601-1692
                                (312) 269-4114

                             ____________________

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
================================================================================================================================
                                                                   Proposed             Proposed
                                                                   Maximum              Maximum
                                             Amount To Be       Offering Price          Aggregate            Amount of
     Title of Securities To Be Registered     Registered        Per Share /(1)/    Offering Price /(1)/  Registration Fee
--------------------------------------------------------------------------------------------------------------------------------
  <S>                                        <C>                <C>                <C>                   <C>
  Common Stock, par value $.01 per share       1,768,000           $17.98           $31,788,640.00          $8,838.00
                                                shares
================================================================================================================================
</TABLE>

(1)  Estimated solely for the purpose of calculating the amount of the
     registration fee, pursuant to paragraphs (c) and (h) of Rule 457 under the
     Securities Act, on the basis of the average of high and low sale prices of
     the shares of Common Stock, par value $.01 per share, of the Company (the
     "Common Stock"), on the Nasdaq Market on July 28, 1999.

================================================================================
<PAGE>

                                    PART II
                                    =======

               Information Required in the Registration Statement

Item 3. Incorporation of Documents by Reference

        The following documents filed by Focal Communications Corporation (the
"Company" or the "Registrant") with the Securities and Exchange Commission (the
"Commission") are incorporated by reference in this Registration Statement:

           (a)  The Company's Annual Report on Form 10-K for the year ended
        December 31, 1998, filed with the Commission on March 31, 1999, as
        amended on Form 10-K/A, filed with the Commission on April 7, 1999;

           (b)  The Company's Quarterly Report on Form 10-Q for the quarter
        ended March 31, 1999, filed with the Commission on May 7, 1999, as
        amended on Form 10-Q/A, filed with the Commission on July 6, 1999; and

           (c)  The description of the Company's Common Stock contained in the
        Company's Registration Statement on Form 8-A, filed with the Commission
        on July 26, 1999 (Reg. No. 000-26821) (the "Form 8-A").

        All other documents filed by the Company pursuant to Sections 13(a),
13(c), 14 and 15(d) of the Exchange Act subsequent to the date of this
Registration Statement and prior to the filing of a post-effective amendment
indicating that all securities offered under this Registration Statement have
been sold, or deregistering all securities then remaining unsold, are also
incorporated by reference and shall be a part hereof from the date of filing of
such documents.

        Any statement contained in a document incorporated or deemed to be
incorporated by reference herein shall be deemed to be modified or superceded
for purposes of this Registration Statement to the extent that a statement
contained herein or in any subsequently filed document which also is or is
deemed to be incorporated by reference herein modifies or supercedes such
statement.  Any such statement so modified or superceded shall not be deemed,
except as so modified or superceded, to constitute a part of this Registration
Statement.

Item 4. Description of Securities.

       Not applicable.

Item 5. Interests of Named Experts and Counsel

       Not applicable.

Item 6. Indemnification of Directors and Officers

        We have statutory authority to indemnify our officers and directors. The
applicable provisions of the Delaware General Corporation Law state that, to the
extent an officer or director is successful on the merits or otherwise, a
corporation may indemnify any person who
<PAGE>

was or is a party or who is threatened to be made a party to any threatened,
pending or completed action, suit or proceeding, whether civil, criminal,
administrative or investigative (other than an action by or in the right of the
corporation), by reason of the fact that he is or was a director, officer,
employee or agent of the corporation or is or was serving at the request of the
corporation as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise (each, a "Person"),
against expenses (including attorneys' fees), judgments, fines and amounts paid
in settlement, actually and reasonably incurred by such Person, if he acted in
good faith and in a manner he reasonably believed to be in, or not opposed to,
the best interests of the corporation and with respect to any criminal action or
proceeding, had no reasonable cause to believe his conduct was unlawful. In any
threatened, pending or completed action by or in the right of the corporation, a
corporation also may indemnify any such Person for costs actually and reasonably
incurred by him in connection with that action's defense or settlement, if he
acted in good faith and in a manner he reasonably believed to be in or not
opposed to, the best interests of the corporation; however, no indemnification
shall be made with respect to any claim, issue or matter as to which such Person
shall have been adjudged to be liable to the corporation, unless and only to the
extent that a court shall determine that such indemnity is proper.

     Under the applicable provisions of the Delaware General Corporation Law,
any indemnification shall be made by the corporation only as authorized in the
specific case upon a determination that the indemnification of the director,
officer, employee or agent is proper in the circumstances because he has met the
applicable standard of conduct. Such determination shall be made:

          (1)  By the Board of Directors by a majority vote of the directors who
     are not parties to such action, suit or proceeding, even if less than a
     quorum;

          (2)  By a committee of such directors designated by a majority vote of
     the directors who are not parties to such action, suit or proceeding, even
     if less than a quorum;

          (3)  If there are no such directors, or if such directors so direct,
     by independent legal counsel in a written opinion; or

          (4)  By the stockholders.

     The Company's certificate of incorporation and bylaws provide for
indemnification to the full extent permitted by the laws of the State of
Delaware against and with respect to threatened, pending or completed actions,
suits or proceedings arising from or alleged to arise from, a party's actions or
omissions as a director, officer, employee or agent of the Company or of any
subsidiary of the Company or of any other corporation, partnership, joint
venture, trust or other entity which he has served in such capacity at the
request of the Company if such acts or omissions occurred or were or are alleged
to have occurred, while said party was a director, officer, employee or agent of
the Company.

     In addition, the Company maintains liability insurance for its directors
and officers.

                                       2
<PAGE>

Item 7.  Exemption from Registration Claimed.

       Not applicable.

Item 8.  Exhibits

Exhibit Number      Description
--------------      -----------

4.1                 Amended and Restated Certificate of Incorporation
                    (incorporated by reference to Exhibit No. 3.3 to the
                    Company's Registration Statement on Form S-1 originally
                    filed with the Commission on May 7, 1999 (Registration No.
                    333-77995) (the "S-1"))

4.2                 Amended and Restated By-Laws (incorporated by reference to
                    Exhibit No. 3.5 of the S-1)

4.3                 Indenture with Harris Trust and Savings Bank, dated February
                    18, 1998 (incorporated by reference to Exhibit No. 4.1 to
                    the Company's Registration Statement on Form S-4 originally
                    filed with the Commission on August 13, 1998 (Registration
                    No. 333-49397) (the "S-4"))

4.4                 Initial Global 12.125% Senior Discount Note Due February 15,
                    2008, dated Februrary 18, 1998 (incorporated by reference to
                    Exhibit No. 4.2 of the S-4)

4.5                 Stock Purchase Agreement with Madison Dearborn Capital
                    Partners, L.P., Frontenac VI, L.P., Battery Ventures III,
                    L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty, and
                    Robert C. Taylor Jr., dated November 27,1996 (incorporated
                    by reference to Exhibit No. 4.5 of the S-4)


4.6                 Amendment No. 1 to Stock Purchase Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated January 23, 1998
                    (incorporated by reference to Exhibit No. 4.6 of the S-4)


4.7                 Amendment No. 2 to Stock Purchase Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P.,
                    Battery Ventures III, L.P., Brian F. Addy, John R.
                    Barnicle, Joseph Beatty, and Robert C. Taylor Jr., dated
                    as of August 21, 1998 (incorporated by reference to Exhibit
                    No. 4.8 to the Company's Quarterly Report on Form 10-Q for
                    the period ending September 30, 1998, originally filed with
                    the Securities and Exchange Commission on November 16, 1998
                    (the "3rd Quarter 1998 10-Q"))

4.8                 Vesting Agreement with Madison Dearborn Capital Partners,
                    L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty and
                    Robert C. Taylor, Jr., dated as of November 27, 1996
                    (incorporated by reference to Exhibit No. 4.1 of the 3rd
                    Quarter 1998 10-Q)

                                       3
<PAGE>

4.9                 Vesting Agreement with Frontenac VI, L.P., Brian F. Addy,
                    John R. Barnicle, Joseph Beatty and Robert C. Taylor, Jr.,
                    dated as of November 27, 1996 (incorporated by reference to
                    Exhibit No. 4.2 of the 3rd Quarter 1998 10-Q)

4.10                Vesting Agreement with Battery Ventures III, L.P., Brian F.
                    Addy, John R. Barnicle, Joseph Beatty and Robert C. Taylor,
                    Jr., dated as of November 27, 1996 (incorporated by
                    reference to Exhibit No. 4.3 of the 3rd Quarter 1998 10-Q)

4.11                Amendment No. 1 to Vesting Agreement and Consent as of
                    August 21, 1998, between the Company and Madison Dearborn
                    Capital Partners, L.P., Frontenac VI, L.P., Battery Ventures
                    III, L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty
                    and Robert C. Taylor, Jr., dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.4 of the 3rd
                    Quarter 1998 10-Q)

4.12                Amendment No. 1 to Vesting Agreement and Consent as of
                    August 21, 1998, between the Company and Madison Dearborn
                    Capital Partners, L.P., Frontenac VI, L.P., Battery Ventures
                    III, L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty
                    and Robert C. Taylor, Jr., dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.5 of the 3rd
                    Quarter 1998 10-Q)

4.13                Amendment No. 1 to Vesting Agreement and Consent as of
                    August 21, 1998, between the Company and Madison Dearborn
                    Capital Partners, L.P., Frontenac VI, L.P., Battery Ventures
                    III, L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty
                    and Robert C. Taylor, Jr., dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.6 of the 3rd
                    Quarter 1998 10-Q)

 4.14               Form of Restricted Stock Agreement, dated September 30, 1998
                    between the Company and each of Brian F. Addy, John R.
                    Barnicle, Joseph Beatty, and Robert C. Taylor, Jr.
                    (incorporated by reference to Exhibit No. 4.7 of the 3rd
                    Quarter 1998 10-Q)

4.15                Stockholders Agreement with Madison Dearborn Capital
                    Partners, L.P., Frontenac VI, L.P., Battery Ventures III,
                    L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty, and
                    Robert C. Taylor Jr., dated November 27, 1996 (incorporated
                    by reference to Exhibit No. 4.11 of the S-4)

4.16                Amendment No. 1 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of July 7, 1998
                    (incorporated by reference to Exhibit No. 4.9 of the 3rd
                    Quarter 1998 10-Q)

                                       4
<PAGE>

4.17                Amendment No. 2 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of August 21,
                    1998 (incorporated by reference to Exhibit No. 4.10 of the
                    3rd Quarter 1998 10- Q)

4.18                Amendment No. 3 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of February 16,
                    1999 (incorporated by reference to Exhibit No. 4.16 to the
                    Company's Annual Report on Form 10-K for year ended December
                    31, 1998 originally filed with the Commission on March 31,
                    1998 (the "1998 10-K"))

4.19                Executive Stock Agreement and Employment Agreement
                    with Brian F. Addy, dated November 27, 1996 (incorporated
                    by reference to Exhibit No. 4.12 of the S-4)

4.20                Executive Stock Agreement and Employment Agreement
                    with John R. Barnicle, dated November 27, 1996
                    (incorporated by reference to Exhibit No. 4.13 of the S-4)

4.21                Executive Stock Agreement and Employment Agreement with
                    Joseph A. Beatty, dated November 27, 1996 (incorporated by
                    reference to Exhibit No. 4.14 of the S-4)

4.22                Executive Stock Agreement and Employment Agreement with
                    Robert C. Taylor, Jr., dated November 27, 1996 (incorporated
                    by reference to Exhibit No. 4.15 of the S-4)

4.23                Amendment No. 1 to Executive Employment Agreement and
                    Consent with Brian F. Addy, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.11 of the 3rd
                    Quarter 1998 10-Q)

4.24                Amendment No. 1 to Executive Employment Agreement and
                    Consent with John R. Barnicle, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.12 of the 3rd
                    Quarter 1998 10-Q)

4.25                Amendment No. 1 to Executive Employment Agreement and
                    Consent with Joseph Beatty, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.13 of the 3rd
                    Quarter 1998 10-Q)

4.26                Amendment No. 1 to Executive Employment Agreement and
                    Consent with Robert C. Taylor, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.14 of the 3rd
                    Quarter 1998 10-Q)

4.27                Registration Agreement with Madison Dearborn Capital
                    Partners, L.P., Frontenac VI, L.P., Battery Ventures III,
                    L.P., Brian F. Addy, John R.


                                       5
<PAGE>

                    Barnicle, Joseph Beatty, and Robert C. Taylor Jr., dated
                    November 27, 1996 (incorporated by reference to Exhibit No.
                    4.16 of the S-4)

4.28                Amendment No. 1 to Registration Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of August 21,
                    1998 (incorporated by reference to Exhibit No. 4.15 of the
                    3rd Quarter 1998 10-Q)

4.29                Amendment No. 4 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty and Robert C. Taylor, Jr., dated as of May 21, 1999
                    (incorporated by reference to Exhibit No. 4.27 of the S-1)

4.30                1998 Equity and Performance Incentive Plan, as amended and
                    restated effective July 23, 1999

4.31                Form of Non-Qualified Stock Option Agreement for use in
                    connection with the 1998 Equity and Performance Incentive
                    Plan

5.1                 Opinion of Jones, Day, Reavis & Pogue

23.1                Consent of Jones, Day, Reavis & Pogue (included in Exhibit
                    5.1)

23.2                Consent of Independent Public Accountants

24.1                Power of Attorney

Item 9.  Undertakings

     (a) The undersigned Registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this Registration Statement:

             (i)   To include any prospectus required by Section 10(a)(3) of the
         Securities Act;

             (ii)  To reflect in the prospectus any facts or events arising
         after the effective date of the Registration Statement (or the most
         recent post-effective amendment thereof) which, individually or in the
         aggregate, represent a fundamental change in the information set forth
         in the Registration Statement. Notwithstanding the foregoing, any
         increase or decrease in volume of securities offered (if the total
         dollar value of securities offered would not exceed that which is
         registered) and any deviation from the low or high of the estimated
         maximum offering range may be reflected in the form of prospectus filed
         with the Commission pursuant to Rule 424(b) if, in the aggregate, the
         changes in volume

                                       6
<PAGE>

         and price represent no more than 20 percent change in the maximum
         aggregate offering price set forth in the "Calculation of Registration
         Fee" table in the effective Registration Statement.

               (iii)  To include any material information with respect to the
         plan of distribution not previously disclosed in the Registration
         Statement or any material change to such information in the
         Registration Statement;

         Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
         apply if the Registration Statement is on Form S-3, Form S-8 or Form F-
         3, and the information required to be included in a post-effective
         amendment by those paragraphs is contained in periodic reports filed
         with or furnished to the Commission by the registrant pursuant to
         Section 13 or Section 15(d) of the Exchange Act that are incorporated
         by reference in the Registration Statement.

         (2)   That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

         (3)   To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

     (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
registrant's annual report pursuant to Section 13(a) or 15(d) of the Exchange
Act (and, where applicable, each filing of an employee benefit plan's annual
report pursuant to Section 15(d) of the Exchange Act) that is incorporated by
reference in the Registration Statement shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

     (c) Insofar as indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Act and is, therefore, unenforceable.
In the event that a claim for indemnification against such liabilities (other
than the payment by the registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.

                                       7
<PAGE>

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Chicago, State of Illinois, on August 2, 1999.


                              FOCAL COMMUNICATIONS CORPORATION


                              By:   /s/ Robert C. Taylor
                                 ------------------------
                                        Robert C. Taylor
                                        President and Chief Executive Officer


          Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities and on the
date indicated

<TABLE>
<CAPTION>
             Signature                                 Title                         Date
             ---------                                 -----                         ----
<S>                                           <C>                                 <C>
   /s/ Robert C. Taylor, Jr.                  Director, President and             August 2, 1999
------------------------------------
       Robert C. Taylor, Jr.                      Chief Executive Officer


   /s/ John R. Barnicle                       Director, Executive Vice            August 2, 1999
------------------------------------
       John R. Barnicle                         President and Chief
                                                 Operating Officer


   /s/ Joseph A. Beatty                       Executive Vice President and        August 2, 1999
------------------------------------
       Joseph A. Beatty                         Chief Financial Officer


   /s/ Gregory J. Swanson                             Controller                  August 2, 1999
------------------------------------
       Gregory J. Swanson
</TABLE>

                                       8
<PAGE>

<TABLE>
<S>                                             <C>                  <C>
  /s/  James E. Crawford, III                   Director             August 2, 1999
------------------------------------
       James E. Crawford, III


  /s/  John A. Edwardson                        Director             August 2, 1999
------------------------------------
       John A. Edwardson


  /s/  Paul J. Finnegan                         Director             August 2, 1999
------------------------------------
       Paul J. Finnegan


  /s/  Richard D. Frisbie                       Director             August 2, 1999
------------------------------------
       Richard D. Frisbie


  /s/  James N. Perry, Jr.                      Director             August 2, 1999
------------------------------------
       James N. Perry, Jr.


  /s/  Paul A. Yovovich                         Director             August 2, 1999
------------------------------------
       Paul A. Yovovich
</TABLE>


* Joseph A. Beatty, the undersigned attorney-in-fact, by signing his name
hereto, does hereby sign and execute this Registration Statement on behalf of
the above indicated Registrant and officers and directors thereof (constituting
a majority of the directors) pursuant to a Power of Attorney filed with the
Securities and Exchange Commission.



August 2, 1999                          By:   /s/ Joseph A. Beatty
                                            ----------------------------------
                                                  Joseph A. Beatty
                                                  Executive Vice President and
                                                  Chief Financial Officer


                                       9
<PAGE>

                                 EXHIBIT INDEX

<TABLE>
<CAPTION>
                                                                           Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
<S>             <C>                                                       <C>
4.1             Amended and Restated Certificate of Incorporation         Incorporated by
                (incorporated by reference to Exhibit No. 3.3 to the      reference
                Company's Registration Statement on Form S-1
                originally filed with the Commission on May 7, 1999
                (Registration No. 333-77995) (the "S-1"))

4.2             Amended and Restated By-Laws (incorporated by             Incorporated by
                reference to Exhibit No. 3.5 to the S-1)                  reference

4.3             Indenture with Harris Trust and Savings Bank, dated       Incorporated by
                February 18, 1998 (incorporated by reference to           reference
                Exhibit No. 4.1 to the Company's Registration
                Statement on Form S-4 originally filed with the
                Securities and Exchange Commission on August 13,
                1998 (Registration No. 333-49397) (the "S-4"))

4.4             Initial Global 12.125% Senior Discount Note Due           Incorporated by
                February 15, 2008, dated February 18, 1998                reference
                (incorporated by reference to Exhibit No. 4.2 of the
                S-4)

4.5             Stock Purchase Agreement with Madison Dearborn            Incorporated by
                Capital Partners, L.P., Frontenac VI, L.P., Battery       reference
                Ventures III, L.P., Brian F. Addy, John R. Barnicle,
                Joseph Beatty, and Robert C. Taylor Jr., dated
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.5 of the S-4)

4.6             Amendment No. 1 to Stock Purchase Agreement               Incorporated by
                with Madison Dearborn Capital Partners, L.P.,             reference
                Frontenac VI, L.P., Battery Ventures III, L.P., Brian
                F. Addy, John R. Barnicle, Joseph Beatty, and
                Robert C. Taylor Jr., dated January 23, 1998
                (incorporated by reference to Exhibit No. 4.6 of the
                S-4)
</TABLE>

                                       10
<PAGE>

<TABLE>
<CAPTION>
                                                                           Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
<S>             <C>                                                       <C>
4.7             Amendment No. 2 to Stock Purchase Agreement               Incorporated by
                with Madison Dearborn Capital Partners, L.P.,             reference
                Frontenac VI, L.P., Battery Ventures III, L.P., Brian
                F. Addy, John R. Barnicle, Joseph Beatty, and
                Robert C. Taylor Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.8 to the
                Company's Quarterly Report on Form 10-Q for the
                period ending September 30, 1998, originally filed
                with the Commission on November 16, 1998 (the
                "3rd Quarter 1998 10-Q"))

4.8             Vesting Agreement with Madison Dearborn Capital           Incorporated by
                Partners, L.P., Brian F. Addy, John R. Barnicle,          reference
                Joseph Beatty and Robert C. Taylor, Jr., dated as of
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.1 of the 3rd Quarter 1998 10-Q)

4.9             Vesting Agreement with Frontenac VI, L.P.,                Incorporated by
                Brian F. Addy, John R. Barnicle, Joseph Beatty and        reference
                Robert C. Taylor, Jr., dated as of November 27,
                1996 (incorporated by reference to Exhibit No. 4.2
                of the 3rd Quarter 1998 10-Q)

4.10            Vesting Agreement with Battery Ventures III, L.P.,        Incorporated by
                Brian F. Addy, John R. Barnicle, Joseph Beatty and        reference
                Robert C. Taylor, Jr., dated as of November 27,
                1996 (incorporated by reference to Exhibit No. 4.3
                of the 3rd Quarter 1998 10-Q)

4.11            Amendment No. 1 to Vesting Agreement and                  Incorporated by
                Consent as of August 21, 1998, between the                reference
                Company and Madison Dearborn Capital Partners,
                L.P., Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.4 of the
                3rd Quarter 1998 10-Q)

4.12            Amendment No. 1 to Vesting Agreement and                  Incorporated by
                Consent as of August 21, 1998, between the                reference
                Company and Madison Dearborn Capital Partners,
                L.P., Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.5 of the
                3rd Quarter 1998 10-Q)
</TABLE>

                                       11
<PAGE>

<TABLE>
<CAPTION>
                                                                           Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
<S>             <C>                                                       <C>
4.13            Amendment No.1 to Vesting Agreement and                   Incorporated by
                Consent as of August 21, 1998, between the                reference
                Company and Madison Dearborn Capital Partners,
                L.P., Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.6 of the
                3rd Quarter 1998 10-Q)

4.14            Form of Restricted Stock Agreement, dated                 Incorporated by
                September 30, 1998 between the Company and each           reference
                of Brian F. Addy, John R. Barnicle, Joseph Beatty,
                and Robert C. Taylor, Jr. (incorporated by reference
                to Exhibit No. 4.7 of the 3rd Quarter 1998 10-Q)

4.15            Stockholders Agreement with Madison Dearborn              Incorporated by
                Capital Partners, L.P., Frontenac VI, L.P., Battery       reference
                Ventures III, L.P., Brian F. Addy, John R. Barnicle,
                Joseph Beatty, and Robert C. Taylor Jr., dated
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.11 of the S-4)

4.16            Amendment No. 1 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of July 7, 1998 (incorporated by
                reference to Exhibit No. 4.9 of the 3rd Quarter 1998
                10-Q)

4.17            Amendment No. 2 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.10 of
                the 3rd Quarter 1998 10-Q)

4.18            Amendment No. 3 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of February 16, 1999
                (incorporated by reference to Exhibit No. 4.16 to
                the Company's Annual Report on Form 10-K for
                year ended December 31, 1998 originally filed with
                the Commission on March 31, 1998 (the "1998 10-
                K"))
</TABLE>

                                       12
<PAGE>

<TABLE>
<CAPTION>
                                                                           Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
<S>             <C>                                                       <C>
4.19            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with Brian F. Addy, dated November 27,          reference
                1996 (incorporated by reference to Exhibit No. 4.12
                of the S-4)

4.20            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with John R. Barnicle, dated November           reference
                27, 1996 (incorporated by reference to Exhibit No.
                4.13 of the S-4)

4.21            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with Joseph A. Beatty, dated November           reference
                27, 1996 (incorporated by reference to Exhibit No.
                4.14 of the S-4)

4.22            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with Robert C. Taylor, Jr., dated               reference
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.15 of the S-4)

4.23            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with Brian F. Addy, dated           reference
                as of August 21, 1998 (incorporated by reference to
                Exhibit No. 4.11 of the 3rd Quarter 1998 10-Q)

4.24            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with John R. Barnicle,              reference
                dated as of August 21, 1998 (incorporated by
                reference to Exhibit No. 4.12 of the 3rd Quarter
                1998 10-Q)

4.25            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with Joseph Beatty, dated           reference
                as of August 21, 1998 (incorporated by reference to
                Exhibit No. 4.13 of the 3rd Quarter 1998 10-Q)

4.26            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with Robert C. Taylor,              reference
                dated as of August 21, 1998 (incorporated by
                reference to Exhibit No. 4.14 of the 3rd Quarter
                1998 10-Q)

4.27            Registration Agreement with Madison Dearborn              Incorporated by
                Capital Partners, L.P., Frontenac VI, L.P., Battery       reference
                Ventures III, L.P., Brian F. Addy, John R. Barnicle,
                Joseph Beatty, and Robert C. Taylor Jr., dated
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.16 of the S-4)
</TABLE>

                                       13
<PAGE>

<TABLE>
<CAPTION>
                                                                           Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
<S>             <C>                                                       <C>
4.28            Amendment No. 1 to Registration Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.15 of
                the 3rd Quarter 1998 10-Q)

4.29            Amendment No. 4 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P.,                  reference
                Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of May 21, 1999
                (incorporated by reference to Exhibit No. 4.27 of
                the S-1)

4.30            1998 Equity and Performance Incentive Plan, as
                amended and restated effective August 1, 1999                    15

4.31            Form of Non-Qualified Stock Option Agreement for
                use in connection with the 1998 Equity and
                Performance Incentive Plan                                       30

5.1             Opinion of Jones, Day, Reavis & Pogue                            36

23.1            Consent of Jones, Day, Reavis & Pogue (included in
                Exhibit 5.1)                                                     36

23.2            Consent of Independent Public Accountants                        37

24.1            Power of Attorney                                                38
</TABLE>

                                       14
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 43741}]
{"company-data": {"conformed-name": "FOCAL COMMUNICATIONS CORP", "cik": "0001059130", "assigned-sic": "4812", "irs-number": "364167094", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-84261", "film-number": "99676056"}, "business-address": {"street1": "200 NORTH LASALLE ST", "city": "CHICAGO", "state": "IL", "zip": "60601", "phone": "3128958400"}, "mail-address": {"street1": "200 NORTH LASALLE ST", "city": "CHICAGO", "state": "IL", "zip": "60601"}}
As filed with the Securities and Exchange Commission on August 2, 1999

                                                        Registration No. 333-

================================================================================

                      SECURITIES AND EXCHANGE COMMISSION

                            WASHINGTON, D.C. 20549

                             ____________________

                                   FORM S-8
                            REGISTRATION STATEMENT
                                     Under
                          THE SECURITIES ACT OF 1933

                             ____________________

                       FOCAL COMMUNICATIONS CORPORATION
            (Exact Name of Registrant as Specified in Its Charter)

             Delaware                                36-4167094
     State or Other Jurisdiction                  (I.R.S. Employer
     of Incorporation)                            Identification No.)

                     200 North LaSalle Street, Suite 1100
                            Chicago, Illinois 60601
                   (Address of Principal Executive Offices)

                  1998 Equity and Performance Incentive Plan
                           (Full Title of the Plan)

                             ____________________

                               Joseph A. Beatty
             Executive Vice President and Chief Financial Officer
                       Focal Communications Corporation
                     200 North LaSalle Street, Suite 1100
                            Chicago, Illinois 60601
                    (Name and Address of Agent For Service)

                                (312) 895-8400
         (Telephone Number, including Area Code, of Agent For Service)

                                With a copy to:
                             Elizabeth C. Kitslaar
                          Jones, Day, Reavis & Pogue
                                77 West Wacker
                         Chicago, Illinois 60601-1692
                                (312) 269-4114

                             ____________________

                        CALCULATION OF REGISTRATION FEE
================================================================================================================================
                                                                   Proposed             Proposed
                                                                   Maximum              Maximum
                                             Amount To Be       Offering Price          Aggregate            Amount of
     Title of Securities To Be Registered     Registered        Per Share /(1)/    Offering Price /(1)/  Registration Fee
--------------------------------------------------------------------------------------------------------------------------------
Common Stock, par value $.01 per share       1,768,000           $17.98           $31,788,640.00          $8,838.00
                                                shares
================================================================================================================================
(1)  Estimated solely for the purpose of calculating the amount of the
     registration fee, pursuant to paragraphs (c) and (h) of Rule 457 under the
     Securities Act, on the basis of the average of high and low sale prices of
     the shares of Common Stock, par value $.01 per share, of the Company (the
     "Common Stock"), on the Nasdaq Market on July 28, 1999.

================================================================================
PART II
                                    =======

               Information Required in the Registration Statement

Item 3. Incorporation of Documents by Reference

        The following documents filed by Focal Communications Corporation (the
"Company" or the "Registrant") with the Securities and Exchange Commission (the
"Commission") are incorporated by reference in this Registration Statement:

           (a)  The Company's Annual Report on Form 10-K for the year ended
        December 31, 1998, filed with the Commission on March 31, 1999, as
        amended on Form 10-K/A, filed with the Commission on April 7, 1999;

           (b)  The Company's Quarterly Report on Form 10-Q for the quarter
        ended March 31, 1999, filed with the Commission on May 7, 1999, as
        amended on Form 10-Q/A, filed with the Commission on July 6, 1999; and

           (c)  The description of the Company's Common Stock contained in the
        Company's Registration Statement on Form 8-A, filed with the Commission
        on July 26, 1999 (Reg. No. 000-26821) (the "Form 8-A").

        All other documents filed by the Company pursuant to Sections 13(a),
13(c), 14 and 15(d) of the Exchange Act subsequent to the date of this
Registration Statement and prior to the filing of a post-effective amendment
indicating that all securities offered under this Registration Statement have
been sold, or deregistering all securities then remaining unsold, are also
incorporated by reference and shall be a part hereof from the date of filing of
such documents.

        Any statement contained in a document incorporated or deemed to be
incorporated by reference herein shall be deemed to be modified or superceded
for purposes of this Registration Statement to the extent that a statement
contained herein or in any subsequently filed document which also is or is
deemed to be incorporated by reference herein modifies or supercedes such
statement.  Any such statement so modified or superceded shall not be deemed,
except as so modified or superceded, to constitute a part of this Registration
Statement.

Item 4. Description of Securities.

       Not applicable.

Item 5. Interests of Named Experts and Counsel

       Not applicable.

Item 6. Indemnification of Directors and Officers

        We have statutory authority to indemnify our officers and directors. The
applicable provisions of the Delaware General Corporation Law state that, to the
extent an officer or director is successful on the merits or otherwise, a
corporation may indemnify any person who
was or is a party or who is threatened to be made a party to any threatened,
pending or completed action, suit or proceeding, whether civil, criminal,
administrative or investigative (other than an action by or in the right of the
corporation), by reason of the fact that he is or was a director, officer,
employee or agent of the corporation or is or was serving at the request of the
corporation as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise (each, a "Person"),
against expenses (including attorneys' fees), judgments, fines and amounts paid
in settlement, actually and reasonably incurred by such Person, if he acted in
good faith and in a manner he reasonably believed to be in, or not opposed to,
the best interests of the corporation and with respect to any criminal action or
proceeding, had no reasonable cause to believe his conduct was unlawful. In any
threatened, pending or completed action by or in the right of the corporation, a
corporation also may indemnify any such Person for costs actually and reasonably
incurred by him in connection with that action's defense or settlement, if he
acted in good faith and in a manner he reasonably believed to be in or not
opposed to, the best interests of the corporation; however, no indemnification
shall be made with respect to any claim, issue or matter as to which such Person
shall have been adjudged to be liable to the corporation, unless and only to the
extent that a court shall determine that such indemnity is proper.

     Under the applicable provisions of the Delaware General Corporation Law,
any indemnification shall be made by the corporation only as authorized in the
specific case upon a determination that the indemnification of the director,
officer, employee or agent is proper in the circumstances because he has met the
applicable standard of conduct. Such determination shall be made:

          (1)  By the Board of Directors by a majority vote of the directors who
     are not parties to such action, suit or proceeding, even if less than a
     quorum;

          (2)  By a committee of such directors designated by a majority vote of
     the directors who are not parties to such action, suit or proceeding, even
     if less than a quorum;

          (3)  If there are no such directors, or if such directors so direct,
     by independent legal counsel in a written opinion; or

          (4)  By the stockholders.

     The Company's certificate of incorporation and bylaws provide for
indemnification to the full extent permitted by the laws of the State of
Delaware against and with respect to threatened, pending or completed actions,
suits or proceedings arising from or alleged to arise from, a party's actions or
omissions as a director, officer, employee or agent of the Company or of any
subsidiary of the Company or of any other corporation, partnership, joint
venture, trust or other entity which he has served in such capacity at the
request of the Company if such acts or omissions occurred or were or are alleged
to have occurred, while said party was a director, officer, employee or agent of
the Company.

     In addition, the Company maintains liability insurance for its directors
and officers.

                                       2
Item 7.  Exemption from Registration Claimed.

       Not applicable.

Item 8.  Exhibits

Exhibit Number      Description
--------------      -----------

4.1                 Amended and Restated Certificate of Incorporation
                    (incorporated by reference to Exhibit No. 3.3 to the
                    Company's Registration Statement on Form S-1 originally
                    filed with the Commission on May 7, 1999 (Registration No.
                    333-77995) (the "S-1"))

4.2                 Amended and Restated By-Laws (incorporated by reference to
                    Exhibit No. 3.5 of the S-1)

4.3                 Indenture with Harris Trust and Savings Bank, dated February
                    18, 1998 (incorporated by reference to Exhibit No. 4.1 to
                    the Company's Registration Statement on Form S-4 originally
                    filed with the Commission on August 13, 1998 (Registration
                    No. 333-49397) (the "S-4"))

4.4                 Initial Global 12.125% Senior Discount Note Due February 15,
                    2008, dated Februrary 18, 1998 (incorporated by reference to
                    Exhibit No. 4.2 of the S-4)

4.5                 Stock Purchase Agreement with Madison Dearborn Capital
                    Partners, L.P., Frontenac VI, L.P., Battery Ventures III,
                    L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty, and
                    Robert C. Taylor Jr., dated November 27,1996 (incorporated
                    by reference to Exhibit No. 4.5 of the S-4)

4.6                 Amendment No. 1 to Stock Purchase Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated January 23, 1998
                    (incorporated by reference to Exhibit No. 4.6 of the S-4)

4.7                 Amendment No. 2 to Stock Purchase Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P.,
                    Battery Ventures III, L.P., Brian F. Addy, John R.
                    Barnicle, Joseph Beatty, and Robert C. Taylor Jr., dated
                    as of August 21, 1998 (incorporated by reference to Exhibit
                    No. 4.8 to the Company's Quarterly Report on Form 10-Q for
                    the period ending September 30, 1998, originally filed with
                    the Securities and Exchange Commission on November 16, 1998
                    (the "3rd Quarter 1998 10-Q"))

4.8                 Vesting Agreement with Madison Dearborn Capital Partners,
                    L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty and
                    Robert C. Taylor, Jr., dated as of November 27, 1996
                    (incorporated by reference to Exhibit No. 4.1 of the 3rd
                    Quarter 1998 10-Q)

                                       3
4.9                 Vesting Agreement with Frontenac VI, L.P., Brian F. Addy,
                    John R. Barnicle, Joseph Beatty and Robert C. Taylor, Jr.,
                    dated as of November 27, 1996 (incorporated by reference to
                    Exhibit No. 4.2 of the 3rd Quarter 1998 10-Q)

4.10                Vesting Agreement with Battery Ventures III, L.P., Brian F.
                    Addy, John R. Barnicle, Joseph Beatty and Robert C. Taylor,
                    Jr., dated as of November 27, 1996 (incorporated by
                    reference to Exhibit No. 4.3 of the 3rd Quarter 1998 10-Q)

4.11                Amendment No. 1 to Vesting Agreement and Consent as of
                    August 21, 1998, between the Company and Madison Dearborn
                    Capital Partners, L.P., Frontenac VI, L.P., Battery Ventures
                    III, L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty
                    and Robert C. Taylor, Jr., dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.4 of the 3rd
                    Quarter 1998 10-Q)

4.12                Amendment No. 1 to Vesting Agreement and Consent as of
                    August 21, 1998, between the Company and Madison Dearborn
                    Capital Partners, L.P., Frontenac VI, L.P., Battery Ventures
                    III, L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty
                    and Robert C. Taylor, Jr., dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.5 of the 3rd
                    Quarter 1998 10-Q)

4.13                Amendment No. 1 to Vesting Agreement and Consent as of
                    August 21, 1998, between the Company and Madison Dearborn
                    Capital Partners, L.P., Frontenac VI, L.P., Battery Ventures
                    III, L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty
                    and Robert C. Taylor, Jr., dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.6 of the 3rd
                    Quarter 1998 10-Q)

 4.14               Form of Restricted Stock Agreement, dated September 30, 1998
                    between the Company and each of Brian F. Addy, John R.
                    Barnicle, Joseph Beatty, and Robert C. Taylor, Jr.
                    (incorporated by reference to Exhibit No. 4.7 of the 3rd
                    Quarter 1998 10-Q)

4.15                Stockholders Agreement with Madison Dearborn Capital
                    Partners, L.P., Frontenac VI, L.P., Battery Ventures III,
                    L.P., Brian F. Addy, John R. Barnicle, Joseph Beatty, and
                    Robert C. Taylor Jr., dated November 27, 1996 (incorporated
                    by reference to Exhibit No. 4.11 of the S-4)

4.16                Amendment No. 1 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of July 7, 1998
                    (incorporated by reference to Exhibit No. 4.9 of the 3rd
                    Quarter 1998 10-Q)

                                       4
4.17                Amendment No. 2 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of August 21,
                    1998 (incorporated by reference to Exhibit No. 4.10 of the
                    3rd Quarter 1998 10- Q)

4.18                Amendment No. 3 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of February 16,
                    1999 (incorporated by reference to Exhibit No. 4.16 to the
                    Company's Annual Report on Form 10-K for year ended December
                    31, 1998 originally filed with the Commission on March 31,
                    1998 (the "1998 10-K"))

4.19                Executive Stock Agreement and Employment Agreement
                    with Brian F. Addy, dated November 27, 1996 (incorporated
                    by reference to Exhibit No. 4.12 of the S-4)

4.20                Executive Stock Agreement and Employment Agreement
                    with John R. Barnicle, dated November 27, 1996
                    (incorporated by reference to Exhibit No. 4.13 of the S-4)

4.21                Executive Stock Agreement and Employment Agreement with
                    Joseph A. Beatty, dated November 27, 1996 (incorporated by
                    reference to Exhibit No. 4.14 of the S-4)

4.22                Executive Stock Agreement and Employment Agreement with
                    Robert C. Taylor, Jr., dated November 27, 1996 (incorporated
                    by reference to Exhibit No. 4.15 of the S-4)

4.23                Amendment No. 1 to Executive Employment Agreement and
                    Consent with Brian F. Addy, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.11 of the 3rd
                    Quarter 1998 10-Q)

4.24                Amendment No. 1 to Executive Employment Agreement and
                    Consent with John R. Barnicle, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.12 of the 3rd
                    Quarter 1998 10-Q)

4.25                Amendment No. 1 to Executive Employment Agreement and
                    Consent with Joseph Beatty, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.13 of the 3rd
                    Quarter 1998 10-Q)

4.26                Amendment No. 1 to Executive Employment Agreement and
                    Consent with Robert C. Taylor, dated as of August 21, 1998
                    (incorporated by reference to Exhibit No. 4.14 of the 3rd
                    Quarter 1998 10-Q)

4.27                Registration Agreement with Madison Dearborn Capital
                    Partners, L.P., Frontenac VI, L.P., Battery Ventures III,
                    L.P., Brian F. Addy, John R.

                                       5
Barnicle, Joseph Beatty, and Robert C. Taylor Jr., dated
                    November 27, 1996 (incorporated by reference to Exhibit No.
                    4.16 of the S-4)

4.28                Amendment No. 1 to Registration Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty, and Robert C. Taylor Jr., dated as of August 21,
                    1998 (incorporated by reference to Exhibit No. 4.15 of the
                    3rd Quarter 1998 10-Q)

4.29                Amendment No. 4 to Stockholders Agreement with Madison
                    Dearborn Capital Partners, L.P., Frontenac VI, L.P., Battery
                    Ventures III, L.P., Brian F. Addy, John R. Barnicle, Joseph
                    Beatty and Robert C. Taylor, Jr., dated as of May 21, 1999
                    (incorporated by reference to Exhibit No. 4.27 of the S-1)

4.30                1998 Equity and Performance Incentive Plan, as amended and
                    restated effective July 23, 1999

4.31                Form of Non-Qualified Stock Option Agreement for use in
                    connection with the 1998 Equity and Performance Incentive
                    Plan

5.1                 Opinion of Jones, Day, Reavis & Pogue

23.1                Consent of Jones, Day, Reavis & Pogue (included in Exhibit
                    5.1)

23.2                Consent of Independent Public Accountants

24.1                Power of Attorney

Item 9.  Undertakings

     (a) The undersigned Registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this Registration Statement:

             (i)   To include any prospectus required by Section 10(a)(3) of the
         Securities Act;

             (ii)  To reflect in the prospectus any facts or events arising
         after the effective date of the Registration Statement (or the most
         recent post-effective amendment thereof) which, individually or in the
         aggregate, represent a fundamental change in the information set forth
         in the Registration Statement. Notwithstanding the foregoing, any
         increase or decrease in volume of securities offered (if the total
         dollar value of securities offered would not exceed that which is
         registered) and any deviation from the low or high of the estimated
         maximum offering range may be reflected in the form of prospectus filed
         with the Commission pursuant to Rule 424(b) if, in the aggregate, the
         changes in volume

                                       6
and price represent no more than 20 percent change in the maximum
         aggregate offering price set forth in the "Calculation of Registration
         Fee" table in the effective Registration Statement.

               (iii)  To include any material information with respect to the
         plan of distribution not previously disclosed in the Registration
         Statement or any material change to such information in the
         Registration Statement;

         Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
         apply if the Registration Statement is on Form S-3, Form S-8 or Form F-
         3, and the information required to be included in a post-effective
         amendment by those paragraphs is contained in periodic reports filed
         with or furnished to the Commission by the registrant pursuant to
         Section 13 or Section 15(d) of the Exchange Act that are incorporated
         by reference in the Registration Statement.

         (2)   That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

         (3)   To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

     (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
registrant's annual report pursuant to Section 13(a) or 15(d) of the Exchange
Act (and, where applicable, each filing of an employee benefit plan's annual
report pursuant to Section 15(d) of the Exchange Act) that is incorporated by
reference in the Registration Statement shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

     (c) Insofar as indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Act and is, therefore, unenforceable.
In the event that a claim for indemnification against such liabilities (other
than the payment by the registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.

                                       7
SIGNATURES

     Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Chicago, State of Illinois, on August 2, 1999.

                              FOCAL COMMUNICATIONS CORPORATION

                              By:   /s/ Robert C. Taylor
                                 ------------------------
                                        Robert C. Taylor
                                        President and Chief Executive Officer

          Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities and on the
date indicated
Signature                                 Title                         Date
             ---------                                 -----                         ----
/s/ Robert C. Taylor, Jr.                  Director, President and             August 2, 1999
------------------------------------
       Robert C. Taylor, Jr.                      Chief Executive Officer

   /s/ John R. Barnicle                       Director, Executive Vice            August 2, 1999
------------------------------------
       John R. Barnicle                         President and Chief
                                                 Operating Officer

   /s/ Joseph A. Beatty                       Executive Vice President and        August 2, 1999
------------------------------------
       Joseph A. Beatty                         Chief Financial Officer

   /s/ Gregory J. Swanson                             Controller                  August 2, 1999
------------------------------------
       Gregory J. Swanson
8
/s/  James E. Crawford, III                   Director             August 2, 1999
------------------------------------
       James E. Crawford, III

  /s/  John A. Edwardson                        Director             August 2, 1999
------------------------------------
       John A. Edwardson

  /s/  Paul J. Finnegan                         Director             August 2, 1999
------------------------------------
       Paul J. Finnegan

  /s/  Richard D. Frisbie                       Director             August 2, 1999
------------------------------------
       Richard D. Frisbie

  /s/  James N. Perry, Jr.                      Director             August 2, 1999
------------------------------------
       James N. Perry, Jr.

  /s/  Paul A. Yovovich                         Director             August 2, 1999
------------------------------------
       Paul A. Yovovich
* Joseph A. Beatty, the undersigned attorney-in-fact, by signing his name
hereto, does hereby sign and execute this Registration Statement on behalf of
the above indicated Registrant and officers and directors thereof (constituting
a majority of the directors) pursuant to a Power of Attorney filed with the
Securities and Exchange Commission.

August 2, 1999                          By:   /s/ Joseph A. Beatty
                                            ----------------------------------
                                                  Joseph A. Beatty
                                                  Executive Vice President and
                                                  Chief Financial Officer

                                       9
EXHIBIT INDEX
Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
4.1             Amended and Restated Certificate of Incorporation         Incorporated by
                (incorporated by reference to Exhibit No. 3.3 to the      reference
                Company's Registration Statement on Form S-1
                originally filed with the Commission on May 7, 1999
                (Registration No. 333-77995) (the "S-1"))

4.2             Amended and Restated By-Laws (incorporated by             Incorporated by
                reference to Exhibit No. 3.5 to the S-1)                  reference

4.3             Indenture with Harris Trust and Savings Bank, dated       Incorporated by
                February 18, 1998 (incorporated by reference to           reference
                Exhibit No. 4.1 to the Company's Registration
                Statement on Form S-4 originally filed with the
                Securities and Exchange Commission on August 13,
                1998 (Registration No. 333-49397) (the "S-4"))

4.4             Initial Global 12.125% Senior Discount Note Due           Incorporated by
                February 15, 2008, dated February 18, 1998                reference
                (incorporated by reference to Exhibit No. 4.2 of the
                S-4)

4.5             Stock Purchase Agreement with Madison Dearborn            Incorporated by
                Capital Partners, L.P., Frontenac VI, L.P., Battery       reference
                Ventures III, L.P., Brian F. Addy, John R. Barnicle,
                Joseph Beatty, and Robert C. Taylor Jr., dated
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.5 of the S-4)

4.6             Amendment No. 1 to Stock Purchase Agreement               Incorporated by
                with Madison Dearborn Capital Partners, L.P.,             reference
                Frontenac VI, L.P., Battery Ventures III, L.P., Brian
                F. Addy, John R. Barnicle, Joseph Beatty, and
                Robert C. Taylor Jr., dated January 23, 1998
                (incorporated by reference to Exhibit No. 4.6 of the
                S-4)
10
Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
4.7             Amendment No. 2 to Stock Purchase Agreement               Incorporated by
                with Madison Dearborn Capital Partners, L.P.,             reference
                Frontenac VI, L.P., Battery Ventures III, L.P., Brian
                F. Addy, John R. Barnicle, Joseph Beatty, and
                Robert C. Taylor Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.8 to the
                Company's Quarterly Report on Form 10-Q for the
                period ending September 30, 1998, originally filed
                with the Commission on November 16, 1998 (the
                "3rd Quarter 1998 10-Q"))

4.8             Vesting Agreement with Madison Dearborn Capital           Incorporated by
                Partners, L.P., Brian F. Addy, John R. Barnicle,          reference
                Joseph Beatty and Robert C. Taylor, Jr., dated as of
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.1 of the 3rd Quarter 1998 10-Q)

4.9             Vesting Agreement with Frontenac VI, L.P.,                Incorporated by
                Brian F. Addy, John R. Barnicle, Joseph Beatty and        reference
                Robert C. Taylor, Jr., dated as of November 27,
                1996 (incorporated by reference to Exhibit No. 4.2
                of the 3rd Quarter 1998 10-Q)

4.10            Vesting Agreement with Battery Ventures III, L.P.,        Incorporated by
                Brian F. Addy, John R. Barnicle, Joseph Beatty and        reference
                Robert C. Taylor, Jr., dated as of November 27,
                1996 (incorporated by reference to Exhibit No. 4.3
                of the 3rd Quarter 1998 10-Q)

4.11            Amendment No. 1 to Vesting Agreement and                  Incorporated by
                Consent as of August 21, 1998, between the                reference
                Company and Madison Dearborn Capital Partners,
                L.P., Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.4 of the
                3rd Quarter 1998 10-Q)

4.12            Amendment No. 1 to Vesting Agreement and                  Incorporated by
                Consent as of August 21, 1998, between the                reference
                Company and Madison Dearborn Capital Partners,
                L.P., Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.5 of the
                3rd Quarter 1998 10-Q)
11
Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
4.13            Amendment No.1 to Vesting Agreement and                   Incorporated by
                Consent as of August 21, 1998, between the                reference
                Company and Madison Dearborn Capital Partners,
                L.P., Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.6 of the
                3rd Quarter 1998 10-Q)

4.14            Form of Restricted Stock Agreement, dated                 Incorporated by
                September 30, 1998 between the Company and each           reference
                of Brian F. Addy, John R. Barnicle, Joseph Beatty,
                and Robert C. Taylor, Jr. (incorporated by reference
                to Exhibit No. 4.7 of the 3rd Quarter 1998 10-Q)

4.15            Stockholders Agreement with Madison Dearborn              Incorporated by
                Capital Partners, L.P., Frontenac VI, L.P., Battery       reference
                Ventures III, L.P., Brian F. Addy, John R. Barnicle,
                Joseph Beatty, and Robert C. Taylor Jr., dated
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.11 of the S-4)

4.16            Amendment No. 1 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of July 7, 1998 (incorporated by
                reference to Exhibit No. 4.9 of the 3rd Quarter 1998
                10-Q)

4.17            Amendment No. 2 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.10 of
                the 3rd Quarter 1998 10-Q)

4.18            Amendment No. 3 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of February 16, 1999
                (incorporated by reference to Exhibit No. 4.16 to
                the Company's Annual Report on Form 10-K for
                year ended December 31, 1998 originally filed with
                the Commission on March 31, 1998 (the "1998 10-
                K"))
12
Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
4.19            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with Brian F. Addy, dated November 27,          reference
                1996 (incorporated by reference to Exhibit No. 4.12
                of the S-4)

4.20            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with John R. Barnicle, dated November           reference
                27, 1996 (incorporated by reference to Exhibit No.
                4.13 of the S-4)

4.21            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with Joseph A. Beatty, dated November           reference
                27, 1996 (incorporated by reference to Exhibit No.
                4.14 of the S-4)

4.22            Executive Stock Agreement and Employment                  Incorporated by
                Agreement with Robert C. Taylor, Jr., dated               reference
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.15 of the S-4)

4.23            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with Brian F. Addy, dated           reference
                as of August 21, 1998 (incorporated by reference to
                Exhibit No. 4.11 of the 3rd Quarter 1998 10-Q)

4.24            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with John R. Barnicle,              reference
                dated as of August 21, 1998 (incorporated by
                reference to Exhibit No. 4.12 of the 3rd Quarter
                1998 10-Q)

4.25            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with Joseph Beatty, dated           reference
                as of August 21, 1998 (incorporated by reference to
                Exhibit No. 4.13 of the 3rd Quarter 1998 10-Q)

4.26            Amendment No. 1 to Executive Employment                   Incorporated by
                Agreement and Consent with Robert C. Taylor,              reference
                dated as of August 21, 1998 (incorporated by
                reference to Exhibit No. 4.14 of the 3rd Quarter
                1998 10-Q)

4.27            Registration Agreement with Madison Dearborn              Incorporated by
                Capital Partners, L.P., Frontenac VI, L.P., Battery       reference
                Ventures III, L.P., Brian F. Addy, John R. Barnicle,
                Joseph Beatty, and Robert C. Taylor Jr., dated
                November 27, 1996 (incorporated by reference to
                Exhibit No. 4.16 of the S-4)
13
Sequentially
Exhibit Number  Description                                                Numbered Page
--------------  -----------                                               ---------------
4.28            Amendment No. 1 to Registration Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P., Frontenac        reference
                VI, L.P., Battery Ventures III, L.P., Brian F. Addy,
                John R. Barnicle, Joseph Beatty, and Robert C.
                Taylor Jr., dated as of August 21, 1998
                (incorporated by reference to Exhibit No. 4.15 of
                the 3rd Quarter 1998 10-Q)

4.29            Amendment No. 4 to Stockholders Agreement with            Incorporated by
                Madison Dearborn Capital Partners, L.P.,                  reference
                Frontenac VI, L.P., Battery Ventures III, L.P.,
                Brian F. Addy, John R. Barnicle, Joseph Beatty and
                Robert C. Taylor, Jr., dated as of May 21, 1999
                (incorporated by reference to Exhibit No. 4.27 of
                the S-1)

4.30            1998 Equity and Performance Incentive Plan, as
                amended and restated effective August 1, 1999                    15

4.31            Form of Non-Qualified Stock Option Agreement for
                use in connection with the 1998 Equity and
                Performance Incentive Plan                                       30

5.1             Opinion of Jones, Day, Reavis & Pogue                            36

23.1            Consent of Jones, Day, Reavis & Pogue (included in
                Exhibit 5.1)                                                     36

23.2            Consent of Independent Public Accountants                        37

24.1            Power of Attorney                                                38
14