<PAGE>   1
    As filed with the Securities and Exchange Commission on October 26, 2000

                                                    Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                              --------------------

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

                              --------------------

                             XO COMMUNICATIONS, INC.
                    (formerly NEXTLINK Communications, Inc.)
             (Exact name of registrant as specified in its charter)


                  Delaware                                 54-1983517
        (State or other jurisdiction                     I.R.S. Employer
      of incorporation or organization)               Identification Number)

   11111 Sunset Hills Road, Reston, Virginia                 22190
   (Address of Principal Executive Offices)                (Zip Code)


             XO COMMUNICATIONS, INC. CASH COMPENSATION DEFERRAL PLAN
                              (Full title of plan)

                              Gary D. Begeman, Esq.
                    Senior Vice President and General Counsel
                             XO Communications, Inc.
                             11111 Sunset Hills Road
                             Reston, Virginia 22190
                     (Name and address of agent for service)

                                 (703) 547-2000
          (Telephone number, including area code, of agent for service)



<TABLE>
<CAPTION>
                                 CALCULATION OF REGISTRATION FEE
===============================================================================================
                          Amount            Proposed            Proposed            Amount of
Title of Securities        to be        Maximum Offering    Maximum Aggregate      Registration
 to be Registered      Registered(1)   Price Per Unit (2)   Offering Price(2)           Fee
-----------------------------------------------------------------------------------------------
<S>                     <C>                    <C>            <C>                     <C>
Deferred Compensation
Obligations             $10,000,000            n/a            $10,000,000             $2,640
===============================================================================================
</TABLE>

(1)    The Deferred Compensation Obligations represent unsecured obligations of
       the Registrant to pay deferred compensation in the future in accordance
       with the provisions of the XO Communications Inc. Cash Compensation
       Deferral Plan. The amount to be registered represents the dollar amount
       of the compensation deferred and deemed invested in accordance with the
       XO Communications, Inc. Cash Compensation Deferral Plan.

(2)    In accordance with Rule 457(h) of the Securities Act of 1933, as amended
       (the "Securities Act"), this estimate is made solely for purposes of
       computing the amount of the registration fee.


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

<PAGE>   2


                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

       The document(s) containing the information specified in this Part I will
be sent or given to employees as specified by Rule 428(b)(l) under the
Securities Act of 1933, as amended (the "Securities Act"). These documents and
the documents incorporated by reference in this Registration Statement pursuant
to Item 3 of Part II of this Registration Statement, taken together, constitute
a prospectus that meets the requirements of Section 10(a) of the Securities Act.


                                     PART II

             INFORMATION NOT REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.   INCORPORATION OF DOCUMENTS BY REFERENCE.

           The following documents heretofore filed by XO Communications, Inc
(the "Company" or "XO") with the Securities and Exchange Commission (the
"Commission") are incorporated herein by reference:

       (i)    Annual Report on Form 10-K for the fiscal year ended December 31,
              1999, filed with the Commission on March 30, 2000;

       (ii)   Quarterly Reports on Form 10-Q for the quarters ended (a) March
              31, 2000, filed with the Commission on May 15, 2000, and (b) June
              30, 2000, filed with the Commission on August 14, 2000; and

       (iii)  Current Reports on Form 8-K filed with the Commission on: (a) July
              20, 2000, and (b) August 21, 2000 (amending the Current Report on
              Form 8-K filed with the Commission on June 22, 2000).

           All documents filed by XO pursuant to Sections 13(a), 13(c), 14 and
15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
subsequent to the filing of this Registration Statement and prior to the filing
of a post-effective amendment indicating that all securities offered under the
Company's Cash Compensation Deferral Plan (the "Plan") have been sold or
deregistering all securities then remaining unsold thereunder shall be deemed to
be incorporated herein by reference and shall be deemed to be a part hereof from
the date of filing thereof.


ITEM 4.   DESCRIPTION OF SECURITIES.

           The securities being registered represent unsecured obligations (the
"Obligations") of the Company to pay to Eligible Employees and Eligible
Directors who participate in the Plan (the "Participants"), upon their
retirement, death, disability, certain change of control events or upon one or
more future date(s) specified by such Participants, salary or bonus (together
with any gains, earnings or losses thereon) the receipt of which the
Participants have elected to defer. The Obligations also may represent amounts
that the Company has elected to contribute to a Participant's account(s) under
the Plan. Amounts deferred or contributed to a Participant's account(s) are
credited with gains, losses and earnings based on hypothetical investment
directions made by the Participant in accordance with investment deferral
crediting options and procedures adopted from time to time pursuant to the Plan.
Any amounts deferred or contributed to a Participant's account with respect to
which a Participant does not provide investment direction shall be credited with
earnings in an amount determined by the Committee (as hereinafter defined) in
its sole discretion or, if an amount is not so determined, such amounts shall
bear interest at the rate applicable to U.S. Treasury Bills having a maturity of
thirty (30) days as in effect from time to time during the relevant period.

           The Plan is administered by the Compensation Committee of the Board
of Directors of the Company (the "Compensation Committee"), which is granted
authority to delegate administration of the Plan to one or more groups,
committees, individuals or entities (the Compensation Committee, together with
any such delegated parties, the "Committee").




<PAGE>   3


           Before the first day of each calendar year (or within 31 days of the
commencement of service for an Eligible Employee or Eligible Director, as the
case may be, whose eligibility to participate in the Plan commences other than
on the first day of a calendar year), or on or before such other date(s) in any
Plan Year that the Committee may, in its sole discretion, establish or designate
for such purpose, a Participant may file with the Committee a deferred
compensation agreement pursuant to which such Participant elects to make
deferrals of base salary and/or bonus compensation for or with respect to such
year, provided that elections to defer bonus compensation payable in 2001 may be
made on or prior to November 15, 2000. Any such Participant election shall be
subject to any maximum or minimum percentage or dollar amount limitations
(which, as of the effective date of the Plan, include a maximum base salary
deferral limit of 90% of a Participant's base salary and a minimum deferral
limitation of $1,000 per year, which limitations may be changed by the Committee
in its sole discretion) and to any other rules prescribed by the Committee in
its sole discretion.

           Any distribution to a Participant of base salary deferrals, bonus
compensation deferrals and Company contributions (together with any gains,
earnings or losses thereon) shall be made as soon as practicable following the
date on which the deferral period for such amounts ends and may be made in a
lump sum or in annual or quarterly installments as directed by the Participant.
The Plan provides for lump-sum distributions of deferrals (i) if a Participant
ceases to be an employee (unless the Committee, in its sole discretion, elects
to defer such distribution and/or make such distribution in installments as
permitted by the Plan or the Participant requests an extended distribution
period and the Committee, in its sole discretion, grants that request), and (ii)
upon the disability or death of the Participant subject, in certain of such
cases, to the right of the Participant or the Participant's beneficiary to elect
or request a different distribution schedule as permitted by the Plan. The Plan
also permits Participants to request certain hardship and other withdrawals
subject to specified limitations and to specified forfeiture and
non-participation requirements contained in the Plan.

           The Obligations are unsecured general obligations of the Company. The
Obligations are not subject to transfer, assignment, hypothecation or
encumbrance. Any attempt by any person to transfer or assign benefits under the
Plan, other than a claim for benefits by a Participant or his or her
beneficiary(ies), will be null and void. There is no trading market for the
Obligations.

           The Obligations are not convertible to any security of the Company.
No trustee has been appointed to take action with respect to the Obligations and
each Participant in the Plan will be responsible for enforcing his or her own
rights with respect to the Obligations. The Company may (but shall not be
obligated to) establish a trust or trusts, or such other funding devices as the
Committee shall deem appropriate, advisable or desirable, which may take the
form of grantor trusts, may be revocable or irrevocable, and may have
independent trustees (such trusts or other funding devices collectively
"Trusts"). Neither Participants nor their beneficiaries or legal representatives
shall have any right, actual or beneficial, other than the right of an unsecured
general creditor, against the Company or against any of such Trusts in respect
of any portion of a Participant's account. The Company has no obligation to make
or to continue to make any contributions to any Trusts that may be established
in connection with the Plan, and any such contributions shall be made (and may
be discontinued) in the sole discretion of the Company. By electing to defer any
amount pursuant to the Plan, each Participant acknowledges and agrees that the
Company shall not be required to make any investment in connection with the Plan
and shall not be required to follow the Participant's hypothetical investment
directions in any actual investment the Company may make or acquire in
connection with the Plan or in determining the amount of any actual or
contingent liability or obligation of the Company thereunder or relating
thereto.


ITEM 5.  INTERESTS OF  NAMED EXPERTS AND COUNSEL.

Not applicable.


ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

           The Company is a Delaware corporation. In its Certificate of
Incorporation, the Company has adopted the provisions of Section 102(b)(7) of
the Delaware General Corporation Law (the "Delaware Law"), which enables a
corporation in its original certificate of incorporation or an amendment thereto
to eliminate or limit the personal liability of a director for monetary damages
for breach of the director's fiduciary duty, except (i) for any breach of the
director's duty of loyalty to the corporation or its stockholders, (ii) for acts
or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law, (iii) pursuant to Section 174 of the Delaware Law




                                       2
<PAGE>   4

(providing for liability of directors for unlawful payment of dividends or
unlawful stock purchases or redemptions) or (iv) for any transaction from which
a director will personally receive a benefit in money, property or services to
which the director is not legally entitled.

           The Company has also adopted indemnification provisions pursuant to
Section 145 of the Delaware Law, which provides that a corporation may indemnify
any persons, including officers and directors, who are, or are threatened to be
made, parties to any threatened, pending or completed legal action, suit or
proceedings, whether civil, criminal, administrative or investigative (other
than an action by or in the right of the corporation), by reason of the fact
that such person was an officer, director, employee or agent of the corporation,
or is or was serving at the request of such corporation as a director, officer,
employee or agent of another corporation or enterprise. The indemnity may
include expenses (including attorney's fees), judgments, fines and amounts paid
in settlement actually and reasonably incurred by such person in connection with
such action, suit or proceeding, provided such officer, director, employee or
agent acted in good faith and in a manner he reasonably believed to be in or not
opposed to the corporation's best interests and, with respect to criminal
proceedings, had no reasonable cause to believe that his conduct was unlawful. A
Delaware corporation may indemnify officers or directors in an action by or in
the right of the corporation under the same conditions, except that no
indemnification is permitted without judicial approval if the officer or
director is adjudged to be liable to the corporation. Where an officer or
director is successful on the merits or otherwise in the defense of any action
referred to above, the corporation must indemnify him against expenses
(including attorney's fees) that such officer or director actually and
reasonably incurred.


ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

           Not applicable.


ITEM 8.  EXHIBITS.

<TABLE>
<CAPTION>

    EXHIBIT
     NUMBER       DESCRIPTION OF EXHIBITS
    -------       -----------------------

<S>               <C>
        4.1    -  XO Communications, Inc. Cash Compensation Deferral Plan.

          5    -  Opinion of Jones, Day, Reavis & Pogue.

       23.1    -  Consent of Jones, Day, Reavis & Pogue (included in Exhibit 5).

       23.2    -  Consent of Arthur Andersen LLP.
</TABLE>


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 was registered) and any deviation from the low or
high end 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 and price represent no more than a 20% change
in the maximum aggregate offering price set forth in the "Calculation of
Registration Fee" table in the effective Registration Statement; and




                                       3
<PAGE>   5



                  (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 (1) (i) and (1) (ii) do not apply if the
Registration Statement is on Form S-3 or Form S-8, 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 Section 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 Securities 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 Securities Act and will be governed by the final
adjudication of such issue.




                                        4
<PAGE>   6



                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, 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 McLean, State of Virginia, on the 26th day of October
2000.

                         XO COMMUNICATIONS, INC.


                         By:/s/ Gary D. Begeman
                            ----------------------------------------
                            Gary D. Begeman
                            Senior Vice President General Counsel and Secretary


        We, the undersigned officers and directors of XO Communications, Inc.,
hereby severally and individually constitute and appoint Mark S. Gunning, Gary
D. Begeman and Richard A. Montfort, Jr., and each of them, as the true and
lawful attorneys-in-fact for the undersigned, in any and all capacities, with
full power of substitution, to sign any and all amendments to this Registration
Statement (including post-effective amendments), and to file the same with
exhibits thereto and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorneys-in-fact, and
each of them, full power and authority to do and perform each and every act and
thing requisite and necessary to be done in and about the premises, as fully to
all intents and purposes as he or she might or could do in person, hereby
ratifying and confirming all that said attorneys-in-fact, or either of them, may
lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, 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/ Daniel F. Akerson         Chairman of the Board and                October 26, 2000
-------------------------     Chief Executive Officer
Daniel F. Akerson             (Principal Executive Officer)




                              President, Chief Operating Officer
-------------------------     and Director
Nathaniel A. Davis




/s/ Mark S. Gunning           Senior Vice President and                October 26, 2000
-------------------------     Chief Financial Officer
Mark S. Gunning               (Principal Financial Officer
                              and Principal Accounting
                              Officer) and Director




/s/ Joseph L. Cole            Director                                 October 26, 2000
-------------------------
Joseph L. Cole



                              Director
-------------------------
Nicholas C. Forstmann
</TABLE>




                                       5
<PAGE>   7

<TABLE>

<S>                           <C>                             <C>
/s/ Sandra J. Horbach         Director                        October 26, 2000
-------------------------
Sandra J. Horbach



                              Director
-------------------------
Nicolas Kauser



/s/ Craig O. McCaw            Director                        October 26, 2000
-------------------------
Craig O. McCaw



/s/ Sharon L. Nelson          Director                        October 26, 2000
-------------------------
Sharon L. Nelson



                              Director
-------------------------
Henry F. Nothhaft




/s/ Jeffrey S. Raikes         Director                        October 26, 2000
-------------------------
Jeffrey S. Raikes




/s/ Peter C. Waal             Director                        October 26, 2000
-------------------------
Peter C. Waal



/s/ Dennis Weibling           Director                        October 26, 2000
-------------------------
Dennis Weibling
</TABLE>



                                      6
<PAGE>   8


                                    EXHIBITS


<TABLE>
<CAPTION>

EXHIBIT
 NUMBER       DESCRIPTION OF EXHIBITS
-------       -----------------------
<S>           <C>
    4.1    -  XO Communications, Inc. Cash Compensation Deferral Plan.

      5    -  Opinion of Jones, Day, Reavis & Pogue.

   23.1    -  Consent of Jones, Day, Reavis & Pogue (included in Exhibit 5).

   23.2    -  Consent of Arthur Andersen LLP.
</TABLE>
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{"company-data": {"conformed-name": "XO COMMUNICATIONS INC", "cik": "0001111634", "assigned-sic": "4813", "irs-number": "541983517", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-48684", "film-number": "746546"}, "business-address": {"street1": "11111 SUNSET HILLS ROAD", "city": "RESTON", "state": "VA", "zip": "22190", "phone": "7035472000"}, "mail-address": {"street1": "11111 SUNSET HILLS ROAD", "city": "RESTON", "state": "VA", "zip": "22190"}, "former-company": [{"former-conformed-name": "NEXTLINK COMMUNICATIONS INC/NEW", "date-changed": "20000622"}, {"former-conformed-name": "NM ACQUISITION CORP", "date-changed": "20000411"}]}
1
    As filed with the Securities and Exchange Commission on October 26, 2000

                                                    Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                              --------------------

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

                              --------------------

                             XO COMMUNICATIONS, INC.
                    (formerly NEXTLINK Communications, Inc.)
             (Exact name of registrant as specified in its charter)

                  Delaware                                 54-1983517
        (State or other jurisdiction                     I.R.S. Employer
      of incorporation or organization)               Identification Number)

   11111 Sunset Hills Road, Reston, Virginia                 22190
   (Address of Principal Executive Offices)                (Zip Code)

             XO COMMUNICATIONS, INC. CASH COMPENSATION DEFERRAL PLAN
                              (Full title of plan)

                              Gary D. Begeman, Esq.
                    Senior Vice President and General Counsel
                             XO Communications, Inc.
                             11111 Sunset Hills Road
                             Reston, Virginia 22190
                     (Name and address of agent for service)

                                 (703) 547-2000
          (Telephone number, including area code, of agent for service)
CALCULATION OF REGISTRATION FEE
===============================================================================================
                          Amount            Proposed            Proposed            Amount of
Title of Securities        to be        Maximum Offering    Maximum Aggregate      Registration
 to be Registered      Registered(1)   Price Per Unit (2)   Offering Price(2)           Fee
-----------------------------------------------------------------------------------------------
Deferred Compensation
Obligations             $10,000,000            n/a            $10,000,000             $2,640
===============================================================================================
(1)    The Deferred Compensation Obligations represent unsecured obligations of
       the Registrant to pay deferred compensation in the future in accordance
       with the provisions of the XO Communications Inc. Cash Compensation
       Deferral Plan. The amount to be registered represents the dollar amount
       of the compensation deferred and deemed invested in accordance with the
       XO Communications, Inc. Cash Compensation Deferral Plan.

(2)    In accordance with Rule 457(h) of the Securities Act of 1933, as amended
       (the "Securities Act"), this estimate is made solely for purposes of
       computing the amount of the registration fee.

================================================================================
2

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

       The document(s) containing the information specified in this Part I will
be sent or given to employees as specified by Rule 428(b)(l) under the
Securities Act of 1933, as amended (the "Securities Act"). These documents and
the documents incorporated by reference in this Registration Statement pursuant
to Item 3 of Part II of this Registration Statement, taken together, constitute
a prospectus that meets the requirements of Section 10(a) of the Securities Act.

                                     PART II

             INFORMATION NOT REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.   INCORPORATION OF DOCUMENTS BY REFERENCE.

           The following documents heretofore filed by XO Communications, Inc
(the "Company" or "XO") with the Securities and Exchange Commission (the
"Commission") are incorporated herein by reference:

       (i)    Annual Report on Form 10-K for the fiscal year ended December 31,
              1999, filed with the Commission on March 30, 2000;

       (ii)   Quarterly Reports on Form 10-Q for the quarters ended (a) March
              31, 2000, filed with the Commission on May 15, 2000, and (b) June
              30, 2000, filed with the Commission on August 14, 2000; and

       (iii)  Current Reports on Form 8-K filed with the Commission on: (a) July
              20, 2000, and (b) August 21, 2000 (amending the Current Report on
              Form 8-K filed with the Commission on June 22, 2000).

           All documents filed by XO pursuant to Sections 13(a), 13(c), 14 and
15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
subsequent to the filing of this Registration Statement and prior to the filing
of a post-effective amendment indicating that all securities offered under the
Company's Cash Compensation Deferral Plan (the "Plan") have been sold or
deregistering all securities then remaining unsold thereunder shall be deemed to
be incorporated herein by reference and shall be deemed to be a part hereof from
the date of filing thereof.

ITEM 4.   DESCRIPTION OF SECURITIES.

           The securities being registered represent unsecured obligations (the
"Obligations") of the Company to pay to Eligible Employees and Eligible
Directors who participate in the Plan (the "Participants"), upon their
retirement, death, disability, certain change of control events or upon one or
more future date(s) specified by such Participants, salary or bonus (together
with any gains, earnings or losses thereon) the receipt of which the
Participants have elected to defer. The Obligations also may represent amounts
that the Company has elected to contribute to a Participant's account(s) under
the Plan. Amounts deferred or contributed to a Participant's account(s) are
credited with gains, losses and earnings based on hypothetical investment
directions made by the Participant in accordance with investment deferral
crediting options and procedures adopted from time to time pursuant to the Plan.
Any amounts deferred or contributed to a Participant's account with respect to
which a Participant does not provide investment direction shall be credited with
earnings in an amount determined by the Committee (as hereinafter defined) in
its sole discretion or, if an amount is not so determined, such amounts shall
bear interest at the rate applicable to U.S. Treasury Bills having a maturity of
thirty (30) days as in effect from time to time during the relevant period.

           The Plan is administered by the Compensation Committee of the Board
of Directors of the Company (the "Compensation Committee"), which is granted
authority to delegate administration of the Plan to one or more groups,
committees, individuals or entities (the Compensation Committee, together with
any such delegated parties, the "Committee").
3

           Before the first day of each calendar year (or within 31 days of the
commencement of service for an Eligible Employee or Eligible Director, as the
case may be, whose eligibility to participate in the Plan commences other than
on the first day of a calendar year), or on or before such other date(s) in any
Plan Year that the Committee may, in its sole discretion, establish or designate
for such purpose, a Participant may file with the Committee a deferred
compensation agreement pursuant to which such Participant elects to make
deferrals of base salary and/or bonus compensation for or with respect to such
year, provided that elections to defer bonus compensation payable in 2001 may be
made on or prior to November 15, 2000. Any such Participant election shall be
subject to any maximum or minimum percentage or dollar amount limitations
(which, as of the effective date of the Plan, include a maximum base salary
deferral limit of 90% of a Participant's base salary and a minimum deferral
limitation of $1,000 per year, which limitations may be changed by the Committee
in its sole discretion) and to any other rules prescribed by the Committee in
its sole discretion.

           Any distribution to a Participant of base salary deferrals, bonus
compensation deferrals and Company contributions (together with any gains,
earnings or losses thereon) shall be made as soon as practicable following the
date on which the deferral period for such amounts ends and may be made in a
lump sum or in annual or quarterly installments as directed by the Participant.
The Plan provides for lump-sum distributions of deferrals (i) if a Participant
ceases to be an employee (unless the Committee, in its sole discretion, elects
to defer such distribution and/or make such distribution in installments as
permitted by the Plan or the Participant requests an extended distribution
period and the Committee, in its sole discretion, grants that request), and (ii)
upon the disability or death of the Participant subject, in certain of such
cases, to the right of the Participant or the Participant's beneficiary to elect
or request a different distribution schedule as permitted by the Plan. The Plan
also permits Participants to request certain hardship and other withdrawals
subject to specified limitations and to specified forfeiture and
non-participation requirements contained in the Plan.

           The Obligations are unsecured general obligations of the Company. The
Obligations are not subject to transfer, assignment, hypothecation or
encumbrance. Any attempt by any person to transfer or assign benefits under the
Plan, other than a claim for benefits by a Participant or his or her
beneficiary(ies), will be null and void. There is no trading market for the
Obligations.

           The Obligations are not convertible to any security of the Company.
No trustee has been appointed to take action with respect to the Obligations and
each Participant in the Plan will be responsible for enforcing his or her own
rights with respect to the Obligations. The Company may (but shall not be
obligated to) establish a trust or trusts, or such other funding devices as the
Committee shall deem appropriate, advisable or desirable, which may take the
form of grantor trusts, may be revocable or irrevocable, and may have
independent trustees (such trusts or other funding devices collectively
"Trusts"). Neither Participants nor their beneficiaries or legal representatives
shall have any right, actual or beneficial, other than the right of an unsecured
general creditor, against the Company or against any of such Trusts in respect
of any portion of a Participant's account. The Company has no obligation to make
or to continue to make any contributions to any Trusts that may be established
in connection with the Plan, and any such contributions shall be made (and may
be discontinued) in the sole discretion of the Company. By electing to defer any
amount pursuant to the Plan, each Participant acknowledges and agrees that the
Company shall not be required to make any investment in connection with the Plan
and shall not be required to follow the Participant's hypothetical investment
directions in any actual investment the Company may make or acquire in
connection with the Plan or in determining the amount of any actual or
contingent liability or obligation of the Company thereunder or relating
thereto.

ITEM 5.  INTERESTS OF  NAMED EXPERTS AND COUNSEL.

Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

           The Company is a Delaware corporation. In its Certificate of
Incorporation, the Company has adopted the provisions of Section 102(b)(7) of
the Delaware General Corporation Law (the "Delaware Law"), which enables a
corporation in its original certificate of incorporation or an amendment thereto
to eliminate or limit the personal liability of a director for monetary damages
for breach of the director's fiduciary duty, except (i) for any breach of the
director's duty of loyalty to the corporation or its stockholders, (ii) for acts
or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law, (iii) pursuant to Section 174 of the Delaware Law

                                       2
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(providing for liability of directors for unlawful payment of dividends or
unlawful stock purchases or redemptions) or (iv) for any transaction from which
a director will personally receive a benefit in money, property or services to
which the director is not legally entitled.

           The Company has also adopted indemnification provisions pursuant to
Section 145 of the Delaware Law, which provides that a corporation may indemnify
any persons, including officers and directors, who are, or are threatened to be
made, parties to any threatened, pending or completed legal action, suit or
proceedings, whether civil, criminal, administrative or investigative (other
than an action by or in the right of the corporation), by reason of the fact
that such person was an officer, director, employee or agent of the corporation,
or is or was serving at the request of such corporation as a director, officer,
employee or agent of another corporation or enterprise. The indemnity may
include expenses (including attorney's fees), judgments, fines and amounts paid
in settlement actually and reasonably incurred by such person in connection with
such action, suit or proceeding, provided such officer, director, employee or
agent acted in good faith and in a manner he reasonably believed to be in or not
opposed to the corporation's best interests and, with respect to criminal
proceedings, had no reasonable cause to believe that his conduct was unlawful. A
Delaware corporation may indemnify officers or directors in an action by or in
the right of the corporation under the same conditions, except that no
indemnification is permitted without judicial approval if the officer or
director is adjudged to be liable to the corporation. Where an officer or
director is successful on the merits or otherwise in the defense of any action
referred to above, the corporation must indemnify him against expenses
(including attorney's fees) that such officer or director actually and
reasonably incurred.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

           Not applicable.

ITEM 8.  EXHIBITS.
EXHIBIT
     NUMBER       DESCRIPTION OF EXHIBITS
    -------       -----------------------
4.1    -  XO Communications, Inc. Cash Compensation Deferral Plan.

          5    -  Opinion of Jones, Day, Reavis & Pogue.

       23.1    -  Consent of Jones, Day, Reavis & Pogue (included in Exhibit 5).

       23.2    -  Consent of Arthur Andersen LLP.
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 was registered) and any deviation from the low or
high end 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 and price represent no more than a 20% change
in the maximum aggregate offering price set forth in the "Calculation of
Registration Fee" table in the effective Registration Statement; and

                                       3
5

                  (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 (1) (i) and (1) (ii) do not apply if the
Registration Statement is on Form S-3 or Form S-8, 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 Section 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 Securities 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 Securities Act and will be governed by the final
adjudication of such issue.

                                        4
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                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, 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 McLean, State of Virginia, on the 26th day of October
2000.

                         XO COMMUNICATIONS, INC.

                         By:/s/ Gary D. Begeman
                            ----------------------------------------
                            Gary D. Begeman
                            Senior Vice President General Counsel and Secretary

        We, the undersigned officers and directors of XO Communications, Inc.,
hereby severally and individually constitute and appoint Mark S. Gunning, Gary
D. Begeman and Richard A. Montfort, Jr., and each of them, as the true and
lawful attorneys-in-fact for the undersigned, in any and all capacities, with
full power of substitution, to sign any and all amendments to this Registration
Statement (including post-effective amendments), and to file the same with
exhibits thereto and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorneys-in-fact, and
each of them, full power and authority to do and perform each and every act and
thing requisite and necessary to be done in and about the premises, as fully to
all intents and purposes as he or she might or could do in person, hereby
ratifying and confirming all that said attorneys-in-fact, or either of them, may
lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration
Statement has been signed by the following persons in the capacities and on the
date indicated.
SIGNATURE                       TITLE                                 DATE
      ---------                       -----                                 ----
/s/ Daniel F. Akerson         Chairman of the Board and                October 26, 2000
-------------------------     Chief Executive Officer
Daniel F. Akerson             (Principal Executive Officer)

                              President, Chief Operating Officer
-------------------------     and Director
Nathaniel A. Davis

/s/ Mark S. Gunning           Senior Vice President and                October 26, 2000
-------------------------     Chief Financial Officer
Mark S. Gunning               (Principal Financial Officer
                              and Principal Accounting
                              Officer) and Director

/s/ Joseph L. Cole            Director                                 October 26, 2000
-------------------------
Joseph L. Cole

                              Director
-------------------------
Nicholas C. Forstmann
5
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/s/ Sandra J. Horbach         Director                        October 26, 2000
-------------------------
Sandra J. Horbach

                              Director
-------------------------
Nicolas Kauser

/s/ Craig O. McCaw            Director                        October 26, 2000
-------------------------
Craig O. McCaw

/s/ Sharon L. Nelson          Director                        October 26, 2000
-------------------------
Sharon L. Nelson

                              Director
-------------------------
Henry F. Nothhaft

/s/ Jeffrey S. Raikes         Director                        October 26, 2000
-------------------------
Jeffrey S. Raikes

/s/ Peter C. Waal             Director                        October 26, 2000
-------------------------
Peter C. Waal

/s/ Dennis Weibling           Director                        October 26, 2000
-------------------------
Dennis Weibling
6
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                                    EXHIBITS
EXHIBIT
 NUMBER       DESCRIPTION OF EXHIBITS
-------       -----------------------
4.1    -  XO Communications, Inc. Cash Compensation Deferral Plan.

      5    -  Opinion of Jones, Day, Reavis & Pogue.

   23.1    -  Consent of Jones, Day, Reavis & Pogue (included in Exhibit 5).

   23.2    -  Consent of Arthur Andersen LLP.