<PAGE>

        As filed with the Securities and Exchange Commission on April 18, 2000
                                                  Registration No. _____________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                            ______________________

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

                            ______________________

                                 XIRCOM, INC.
              (Exact name of issuer as specified in its charter)

          CALIFORNIA                                      95-4221884
   ------------------------                   ---------------------------------
   (STATE OF INCORPORATION)                   (IRS EMPLOYER IDENTIFICATION NO.)

                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                   (Address of Principal Executive Offices)

                             ______________________

                                2000 STOCK PLAN

                           (Full title of the plan)

                            ______________________

                              Steven F. DeGennaro
                            Chief Financial Officer
                                 XIRCOM, INC.
                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                    (Name and address of agent for service)
                                (805) 376-9300
         (Telephone number, including area code, of agent for service)

                             ______________________

                                   Copy to:
                            Howard S. Zeprun, Esq.
                       WILSON SONSINI GOODRICH & ROSATI
                           Professional Corporation
                              650 Page Mill Road
                          Palo Alto, California 94304
                          Telephone:  (650) 493-9300
<PAGE>

                        CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------
    Title of                             Proposed              Proposed
Securities to be         Amount to    Maximum Offering     Maximum Aggregate        Amount of
   Registered         be Registered   Price Per Share      Offering Price        Registration Fee
-------------------------------------------------------------------------------------------------
<S>                   <C>             <C>                  <C>                   <C>
 Common Stock,
 $0.001 par value
    Upon exercise
    of options        1,200,000 shs.   $31.34375(1)          $37,612,500(1)       $9,929.70
    under the 2000
    Stock Plan

 TOTAL........................................................................... $9,929.70
</TABLE>

______________________
(1)  Estimated in accordance with Rule 457 solely for the purpose of calculating
     the registration fee on the basis of the average between the high and low
     price of the Registrant's Common Stock as reported on the Nasdaq National
     Market on April 17, 2000.

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

                                 XIRCOM, INC.
                      REGISTRATION STATEMENT ON FORM S-8

                                    PART II

                INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.
         ---------------------------------------

  There are hereby incorporated by reference in this Registration Statement the
following documents and information heretofore filed with the Securities and
Exchange Commission:


  1.   The Company's Annual Report on Form 10-K for the year ended September 30,
1999, filed pursuant to Section 13 of the Securities Exchange Act of 1934, as
amended (the "Exchange Act").

  2.   The Company's Quarterly Report on Form 10-Q for the quarter ended
December 31, 1999, filed pursuant to Section 13 of the Exchange Act.

  3.   The Company's Current Report on Form 8-K dated January 19, 2000, filed
pursuant to Section 13 of the Exchange Act.

  4.   The Company's Current Report on Form 8-K dated March 24, 2000, filed
pursuant to Section 13 of the Exchange Act.

  5.   The description of the Company's Common Stock contained in the Company's
Registration Statement on Form 8-A dated February 11, 1992, filed pursuant to
Section 12 of the Exchange Act, including any amendment or report filed for the
purpose of updating such description.

  All documents filed by the Company pursuant to Sections 13(a), 13(c), 14 and
15(d) of the Exchange Act on or after the date of this Registration Statement
and prior to the filing of a post-effective amendment which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold shall be deemed to be incorporated by reference in this
Registration Statement and to be part hereof from the date of filing of such
documents.

ITEM 6.   INDEMNIFICATION OF DIRECTORS AND OFFICERS.
  ------------------------------------------

  Section 204 of the General Corporation Law of the State of California
("California Law") authorizes a corporation to adopt a provision in its articles
of incorporation eliminating the personal liability of directors to corporations
and their shareholders for monetary damages for breach or alleged breach of
directors' "duty of care."  Following a California corporation's adoption of
such a provision, its directors are not accountable to corporations and their
shareholders for monetary damages for conduct constituting negligence (or gross
negligence) in the exercise of their fiduciary duties; however, directors
continue to be subject to equitable remedies such as injunction or rescission.
Under California Law, a director also continues to be liable for (1) a breach of
his or her duty of loyalty; (2) acts or omissions not in good faith or involving
intentional misconduct or knowing violations of law; (3) illegal payments of
dividends; and (4) approval of any transaction from which a director derives an
improper personal benefit.  The adoption of such a provision in the articles of
incorporation also does not limit directors' liability for violations of the
federal securities laws.

  Section 317 of the California Law makes a provision for the indemnification
of officers, directors and other corporate agents in terms sufficiently broad to
indemnify such persons, under certain circumstances, for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act of 1933,
as amended (the "Securities Act").  An amendment to Section 317 provides that
the indemnification provided by this section is not exclusive to the extent
additional rights are authorized in a corporation's articles of incorporation.

  The Company has adopted provisions in its Amended Articles of Incorporation
which eliminate the liability of its directors for monetary damages and
authorize the Company to indemnify its officers, directors and other agents to
the fullest extent permitted by law.

ITEM 8.  EXHIBITS.
         --------
<PAGE>

     Exhibit
     Number    Description
     -------   -----------
     5.1       Opinion of counsel as to legality of securities being registered.

     23.1      Consent of Ernst & Young LLP, Independent Auditors.

     24.2      Consent of counsel (contained in Exhibit 5.1).

     25.1      Power of Attorney (see page II-4).

     99.1*     Xircom, Inc. 2000 Stock Plan


  * Exhibit 99.1 is incorporated herein by reference to Exhibit 10.36 of
    Registrant's Quarterly Report on Form 10-Q for the quarter ended December
    31, 1999, filed with the Commission.

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 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.

               (2)  That, for the purpose of determining any liability under the
Securities Act of 1933, 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 that 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 Securities and Exchange
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.
<PAGE>

                                  SIGNATURES

   Pursuant to the requirements of the Securities Act of 1993, as amended, 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 Thousand Oaks, State of California, on April 18,
2000.

                              XIRCOM, INC.

                              By: /s/ DIRK I. GATES
                                  ----------------------------------
                                  Dirk I. Gates, Chairman, President
                                  and Chief Executive Officer

                               POWER OF ATTORNEY

   KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Dirk I. Gates and Steven F. DeGennaro, jointly
and severally, his attorneys-in-fact, each with the power of substitution, for
him in any and all capacities, to sign any amendments to this Registration
Statement on Form S-8 and to file the same, with exhibits thereto and other
documents in connection therewith, with the Securities and Exchange Commission,
hereby ratifying and confirming all that each of said attorneys-in-fact, or his
substitution or substitutes, may do or cause to be done by virtue hereof.

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

<TABLE>
<CAPTION>
Signature                                    Title                         Date
---------------------------------     -----------------------------        ---------------
 <S>                                  <C>                                  <C>
 /s/ DIRK I. GATES                    President and Chief Executive        April 18, 2000
 --------------------------------     Officer and Director (Principal
 (Dirk I. Gates)                      Executive Officer)

 /s/ STEVEN F. DEGENNARO              Vice President, Finance and          April 18, 2000
 --------------------------------     Chief Financial Officer (Principal
 (Steven F. DeGennaro)                Accounting Officer)

 /s/ MICHAEL F. G. ASHBY              Director                             April 18, 2000
 --------------------------------
 (Michael F. G. Ashby)

 /s/ KENNETH J. BIBA                  Director                             April 18, 2000
 --------------------------------
 (Kenneth J. Biba)

 /s/ GARY J. BOWEN                    Director                             April 18, 2000
 --------------------------------
 (Gary J. Bowen)

 /s/ J. KIRK MATHEWS                  Director                             April 18, 2000
---------------------------------
 (J. Kirk Mathews)

 /s/ CARL E. RUSSO                    Director                             April 18, 2000
---------------------------------
 (Carl E. Russo)

 /s/ WILLIAM J. SCHROEDER             Director                             April 18, 2000
---------------------------------
 (William J. Schroeder)

 /s/ DELBERT W. YOCAM                 Director                             April 18, 2000
---------------------------------
(Delbert W. Yocam)
</TABLE>
<PAGE>

                               INDEX TO EXHIBITS


   EXHIBIT
   NUMBER                DESCRIPTION
 ---------    --------------------------------------------------------
    5.1       Opinion of counsel as to legality of securities being registered

   23.1       Consent of Ernst & Young LLP, Independent Auditors

   24.2       Consent of Counsel (Contained in Exhibit 5.1.)

   25.1       Power of Attorney (included in signature pages to this
              registration statement)

   99.1*      Xircom, Inc. 2000 Stock Plan


 * Exhibit 99.1 is incorporated herein by reference to Exhibit 10.36 of
   Registrant's Quarterly Report on Form 10-Q for the quarter ended December 31,
   1999, filed with the Commission.
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 14885}]
{"company-data": {"conformed-name": "XIRCOM INC", "cik": "0000883905", "assigned-sic": "3576", "irs-number": "954221884", "state-of-incorporation": "CA", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-35036", "film-number": "604150"}, "business-address": {"street1": "2300 CORPORATE CENTER DR", "city": "THOUSAND OAKS", "state": "CA", "zip": "91320-1420", "phone": "8053769300"}, "mail-address": {"street1": "2300 CORPORATE CENTER DRIVE", "city": "THOUSAND OAKS", "state": "CA", "zip": "91320-1420"}}
As filed with the Securities and Exchange Commission on April 18, 2000
                                                  Registration No. _____________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                            ______________________

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

                            ______________________

                                 XIRCOM, INC.
              (Exact name of issuer as specified in its charter)

          CALIFORNIA                                      95-4221884
   ------------------------                   ---------------------------------
   (STATE OF INCORPORATION)                   (IRS EMPLOYER IDENTIFICATION NO.)

                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                   (Address of Principal Executive Offices)

                             ______________________

                                2000 STOCK PLAN

                           (Full title of the plan)

                            ______________________

                              Steven F. DeGennaro
                            Chief Financial Officer
                                 XIRCOM, INC.
                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                    (Name and address of agent for service)
                                (805) 376-9300
         (Telephone number, including area code, of agent for service)

                             ______________________

                                   Copy to:
                            Howard S. Zeprun, Esq.
                       WILSON SONSINI GOODRICH & ROSATI
                           Professional Corporation
                              650 Page Mill Road
                          Palo Alto, California 94304
                          Telephone:  (650) 493-9300
CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------------------------
    Title of                             Proposed              Proposed
Securities to be         Amount to    Maximum Offering     Maximum Aggregate        Amount of
   Registered         be Registered   Price Per Share      Offering Price        Registration Fee
-------------------------------------------------------------------------------------------------
Common Stock,
 $0.001 par value
    Upon exercise
    of options        1,200,000 shs.   $31.34375(1)          $37,612,500(1)       $9,929.70
    under the 2000
    Stock Plan

 TOTAL........................................................................... $9,929.70
______________________
(1)  Estimated in accordance with Rule 457 solely for the purpose of calculating
     the registration fee on the basis of the average between the high and low
     price of the Registrant's Common Stock as reported on the Nasdaq National
     Market on April 17, 2000.

================================================================================
XIRCOM, INC.
                      REGISTRATION STATEMENT ON FORM S-8

                                    PART II

                INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.
         ---------------------------------------

  There are hereby incorporated by reference in this Registration Statement the
following documents and information heretofore filed with the Securities and
Exchange Commission:

  1.   The Company's Annual Report on Form 10-K for the year ended September 30,
1999, filed pursuant to Section 13 of the Securities Exchange Act of 1934, as
amended (the "Exchange Act").

  2.   The Company's Quarterly Report on Form 10-Q for the quarter ended
December 31, 1999, filed pursuant to Section 13 of the Exchange Act.

  3.   The Company's Current Report on Form 8-K dated January 19, 2000, filed
pursuant to Section 13 of the Exchange Act.

  4.   The Company's Current Report on Form 8-K dated March 24, 2000, filed
pursuant to Section 13 of the Exchange Act.

  5.   The description of the Company's Common Stock contained in the Company's
Registration Statement on Form 8-A dated February 11, 1992, filed pursuant to
Section 12 of the Exchange Act, including any amendment or report filed for the
purpose of updating such description.

  All documents filed by the Company pursuant to Sections 13(a), 13(c), 14 and
15(d) of the Exchange Act on or after the date of this Registration Statement
and prior to the filing of a post-effective amendment which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold shall be deemed to be incorporated by reference in this
Registration Statement and to be part hereof from the date of filing of such
documents.

ITEM 6.   INDEMNIFICATION OF DIRECTORS AND OFFICERS.
  ------------------------------------------

  Section 204 of the General Corporation Law of the State of California
("California Law") authorizes a corporation to adopt a provision in its articles
of incorporation eliminating the personal liability of directors to corporations
and their shareholders for monetary damages for breach or alleged breach of
directors' "duty of care."  Following a California corporation's adoption of
such a provision, its directors are not accountable to corporations and their
shareholders for monetary damages for conduct constituting negligence (or gross
negligence) in the exercise of their fiduciary duties; however, directors
continue to be subject to equitable remedies such as injunction or rescission.
Under California Law, a director also continues to be liable for (1) a breach of
his or her duty of loyalty; (2) acts or omissions not in good faith or involving
intentional misconduct or knowing violations of law; (3) illegal payments of
dividends; and (4) approval of any transaction from which a director derives an
improper personal benefit.  The adoption of such a provision in the articles of
incorporation also does not limit directors' liability for violations of the
federal securities laws.

  Section 317 of the California Law makes a provision for the indemnification
of officers, directors and other corporate agents in terms sufficiently broad to
indemnify such persons, under certain circumstances, for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act of 1933,
as amended (the "Securities Act").  An amendment to Section 317 provides that
the indemnification provided by this section is not exclusive to the extent
additional rights are authorized in a corporation's articles of incorporation.

  The Company has adopted provisions in its Amended Articles of Incorporation
which eliminate the liability of its directors for monetary damages and
authorize the Company to indemnify its officers, directors and other agents to
the fullest extent permitted by law.

ITEM 8.  EXHIBITS.
         --------
Exhibit
     Number    Description
     -------   -----------
     5.1       Opinion of counsel as to legality of securities being registered.

     23.1      Consent of Ernst & Young LLP, Independent Auditors.

     24.2      Consent of counsel (contained in Exhibit 5.1).

     25.1      Power of Attorney (see page II-4).

     99.1*     Xircom, Inc. 2000 Stock Plan

  * Exhibit 99.1 is incorporated herein by reference to Exhibit 10.36 of
    Registrant's Quarterly Report on Form 10-Q for the quarter ended December
    31, 1999, filed with the Commission.

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 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.

               (2)  That, for the purpose of determining any liability under the
Securities Act of 1933, 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 that 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 Securities and Exchange
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.
SIGNATURES

   Pursuant to the requirements of the Securities Act of 1993, as amended, 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 Thousand Oaks, State of California, on April 18,
2000.

                              XIRCOM, INC.

                              By: /s/ DIRK I. GATES
                                  ----------------------------------
                                  Dirk I. Gates, Chairman, President
                                  and Chief Executive Officer

                               POWER OF ATTORNEY

   KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Dirk I. Gates and Steven F. DeGennaro, jointly
and severally, his attorneys-in-fact, each with the power of substitution, for
him in any and all capacities, to sign any amendments to this Registration
Statement on Form S-8 and to file the same, with exhibits thereto and other
documents in connection therewith, with the Securities and Exchange Commission,
hereby ratifying and confirming all that each of said attorneys-in-fact, or his
substitution or substitutes, may do or cause to be done by virtue hereof.

   Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities and on the
dates indicated.
Signature                                    Title                         Date
---------------------------------     -----------------------------        ---------------
/s/ DIRK I. GATES                    President and Chief Executive        April 18, 2000
 --------------------------------     Officer and Director (Principal
 (Dirk I. Gates)                      Executive Officer)

 /s/ STEVEN F. DEGENNARO              Vice President, Finance and          April 18, 2000
 --------------------------------     Chief Financial Officer (Principal
 (Steven F. DeGennaro)                Accounting Officer)

 /s/ MICHAEL F. G. ASHBY              Director                             April 18, 2000
 --------------------------------
 (Michael F. G. Ashby)

 /s/ KENNETH J. BIBA                  Director                             April 18, 2000
 --------------------------------
 (Kenneth J. Biba)

 /s/ GARY J. BOWEN                    Director                             April 18, 2000
 --------------------------------
 (Gary J. Bowen)

 /s/ J. KIRK MATHEWS                  Director                             April 18, 2000
---------------------------------
 (J. Kirk Mathews)

 /s/ CARL E. RUSSO                    Director                             April 18, 2000
---------------------------------
 (Carl E. Russo)

 /s/ WILLIAM J. SCHROEDER             Director                             April 18, 2000
---------------------------------
 (William J. Schroeder)

 /s/ DELBERT W. YOCAM                 Director                             April 18, 2000
---------------------------------
(Delbert W. Yocam)
INDEX TO EXHIBITS

   EXHIBIT
   NUMBER                DESCRIPTION
 ---------    --------------------------------------------------------
    5.1       Opinion of counsel as to legality of securities being registered

   23.1       Consent of Ernst & Young LLP, Independent Auditors

   24.2       Consent of Counsel (Contained in Exhibit 5.1.)

   25.1       Power of Attorney (included in signature pages to this
              registration statement)

   99.1*      Xircom, Inc. 2000 Stock Plan

 * Exhibit 99.1 is incorporated herein by reference to Exhibit 10.36 of
   Registrant's Quarterly Report on Form 10-Q for the quarter ended December 31,
   1999, filed with the Commission.