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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                            ________________________

                                  SCHEDULE 13D
                                 (Rule 13d-101)

  Information to be Included in Statements Filed Pursuant to Rule 13d-1(a) and
               Amendments Thereto Filed Pursuant to Rule 13d-2(a)*

                            ________________________

                              Centra Software, Inc.
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                                (Name of Issuer)

                    Common Stock, Par Value $0.001 Per Share
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                         (Title of Class of Securities)

                                    15234X103
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                                 (CUSIP Number)

                                 David Drummond
                        Executive Vice President and CFO
                                 SmartForce PLC
                              900 Chesapeake Drive
                             Redwood City, CA 94063
                            Telephone: (650) 817-5900

                                    Copy to:

                                Steven V. Bernard
                                Steve L. Camahort
                        Wilson Sonsini Goodrich & Rosati
                               650 Page Mill Road
                               Palo Alto, CA 94304
                            Telephone: (650) 493-9300
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  (Name, Address and Telephone Number of Person Authorized to Receive Notices)

                                January 16, 2002
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             (Date of Event which requires Filing of this Statement)

     If the filing person has previously filed a statement on Schedule 13G to
report the acquisition that is the subject of this Schedule 13D, and is filing
this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the
following box. [_]

     Note: Schedules filed in paper format shall include a signed original and
five copies of the schedule, including all exhibits. See Rule 13d-7(b) for other
parties to whom copies are to be sent.

     *The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter disclosures provided in a prior cover page.

     The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934, as amended (the "Act") or otherwise subject to the liabilities of
that section of the Act but shall be subject to all other provisions of the Act
(however, see the Notes).

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CUSIP NO. 15234X103                  SCHEDULE 13D

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      NAME OF REPORTING PERSONS
 1    I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

      SmartForce PLC

      (I.R.S. Identification No. Not Applicable)
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      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
 2                                                              (a) [_]
                                                                (b) [_]
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      SEC USE ONLY
 3
------------------------------------------------------------------------------
      SOURCE OF FUNDS (See Instructions)
 4
      OO
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      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
      TO ITEM 2(d) or 2(e)                                          [_]
 5
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      CITIZENSHIP OR PLACE OF ORGANIZATION
 6
      Republic of Ireland
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                          SOLE VOTING POWER
                     7
     NUMBER OF            0
      SHARES       -----------------------------------------------------------
                          SHARED VOTING POWER
   BENEFICIALLY      8
     OWNED BY             3,177,361 shares of Common Stock (1)
                   -----------------------------------------------------------
       EACH               SOLE DISPOSITIVE POWER
                     9
    REPORTING             0
      PERSON       -----------------------------------------------------------
                          SHARED DISPOSITIVE POWER
       WITH          10
                          0
------------------------------------------------------------------------------
      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
11
      3,177,361 shares of Common Stock (1)
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      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
12
      (See Instructions)                                            [_]
------------------------------------------------------------------------------
      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
13
      12.2%
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      TYPE OF REPORTING PERSON (See Instructions)
14
      CO
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(1)  3,177,361 shares of common stock, par value $0.001 per share (the " Centra
     Common Stock"), of Centra Software, Inc., a Delaware corporation
     ("Centra"), are subject to voting agreements entered into by SmartForce
     PLC, a public limited liability company organized under the laws of the
     Republic of Ireland ("SmartForce"), and certain stockholders of Centra
     ("Company Voting Agreements") (discussed in Items 3 and 4 below).
     SmartForce expressly disclaims beneficial ownership of any of the shares of
     Centra Common Stock covered by the Company Voting Agreements. Based on the
     number of shares of Centra Common Stock outstanding as of January 15, 2002
     (as represented by Centra in the Merger Agreement discussed in Items 3 and
     4), the number of shares of Centra Common Stock covered by the Company
     Voting Agreements represents approximately 12.2% of the outstanding Centra
     Common Stock.



Item 1.       Security and Issuer.

     The class of securities to which this Statement relates is the common
stock, par value $0.001 per share of Centra Software, Inc., a Delaware
corporation, whose principal executive offices are located at 430 Bedford
Street, Lexington, MA 02420.

Item 2. Identity and Background.

     (a)  SmartForce PLC, a public limited liability company organized under the
laws of the Republic of Ireland.

     (b)  SmartForce's principal executive offices are located at 900 Chesapeake
Drive, Redwood City, CA 94063.

     (c)  SmartForce is a provider of comprehensive integrated e-learning
solutions that help businesses support their critical strategic business
initiatives and deploy knowledge globally across their extended enterprise of
employees, customers, suppliers, distributors and other business partners.

          The name, business address, present principal occupation or
employment, the name and principal business of any corporation or other
organization in which such employment is conducted and the citizenship of each
director and executive officer of SmartForce is set forth in Annex A hereto and
is incorporated herein by reference.

     (d)  During the last five years neither SmartForce, nor to the best of
SmartForce's knowledge, any of the other entities or individuals referred to in
Annex A has been convicted in a criminal proceeding (excluding traffic
violations or similar misdemeanors).

     (e)   During the last five years neither SmartForce nor, to the best of
SmartForce's knowledge, any of the other entities or individuals referred to in
Annex A was a party to a civil proceeding of a judicial or administrative body
of competent jurisdiction and as a result of such proceeding was or is subject
to a judgment, decree or final order enjoining future violations of, or
prohibiting or mandating activities subject to, federal or state securities laws
or finding any violation with respect to such laws.

     (f)  SmartForce is a public limited liability company organized under the
laws of the Republic of Ireland.

Item 3. Source and Amount of Funds or Other Consideration.

     SmartForce, Centra and Atlantic Acquisition Corp., a Delaware corporation
and a wholly-owned subsidiary of the Company ("Merger Sub"), entered into an
Agreement and Plan of Merger and Reorganization, dated as of January 16, 2002
(the "Merger Agreement"). Pursuant to the Merger Agreement, Merger Sub will be
merged with and into Centra with Centra continuing as the surviving corporation
and a wholly-owned subsidiary of SmartForce (the "Merger"). As a result of the
Merger, each issued and outstanding share of Common Stock, par value $0.001 per
share, of Centra ("Centra Common Stock") will be automatically converted into
the right to receive 0.425 (the "Exchange Ratio") of a validly issued and fully
paid American Depositary Share of SmartForce ("SmartForce ADSs"). Each
SmartForce ADS represents one ordinary share of SmartForce. In addition,
SmartForce will assume all options or other rights to purchase capital stock of
Centra outstanding under Centra's existing stock option plans, excluding
Centra's stock purchase plans, and each such option or other right to purchase
capital stock of Centra will be or will later become exercisable for SmartForce
ADSs rather than shares of Centra Common Stock, in a number adjusted



to reflect the Exchange Ratio, and at an exercise price adjusted to reflect the
Exchange Ratio. The consummation of the Merger is subject to the approval of the
stockholders of SmartForce and Centra, receipt of necessary approvals under
United States and applicable foreign antitrust laws, SEC clearance and other
customary closing conditions. The Merger is intended to be a tax-free
reorganization under Section 368(a) of the Internal Revenue Code of 1986, as
amended.

     Pursuant to the Company Voting Agreement, certain holders of Centra Common
Stock have agreed, severally and not jointly, to grant an irrevocable proxy to
vote their shares of Centra Common Stock (plus any additional shares of Centra
Common Stock or other securities acquired upon the exercise of options, warrants
and other rights to acquire shares of Centra Common Stock) beneficially owned by
each such stockholder (the "Company Voting Agreement Shares") at every Centra
stockholders meeting and every written consent in lieu of such a meeting in
favor of adoption of the Merger Agreement and the approval of other actions
contemplated by the Merger Agreement. The Company Voting Agreements terminate
upon the earlier to occur of (i) the termination of the Merger Agreement and
(ii) the consummation of the Merger. Centra and certain holders of SmartForce
ADSs have also entered into similar agreements. SmartForce did not pay
additional consideration to any Company Voting Agreement stockholder in
connection with the execution and delivery of the Company Voting Agreements.

     References to, and descriptions of, the Merger Agreement and the form of
Company Voting Agreement as set forth above in this Item 3 are qualified in
their entirety by reference to the copies of the Merger Agreement and the form
of Company Voting Agreement listed as Exhibits 1 and 2 to this Schedule 13D, and
are incorporated in this Item 3 in their entirety where such references and
descriptions appear.

Item 4. Purpose of Transaction.

     The information set forth or incorporated by reference in Item 3 is hereby
incorporated by reference.

     Pursuant to the Merger Agreement, the Board of Directors of SmartForce is
required to take all action necessary to appoint Centra's Chairman and Chief
Executive Officer, Leon Navickas, to (i) SmartForce's Board of Directors
immediately after the Effective Time (as defined in the Merger Agreement) and
(ii) the position of Chief Technology Officer of SmartForce effective as of the
Effective Time.

     References to, and descriptions of, the Merger Agreement and the form of
Company Voting Agreement as set forth above in this Item 4 are qualified in
their entirety by reference to the copies of the Merger Agreement and the form
of Company Voting Agreement listed as Exhibits 1 and 2 to this Schedule 13D, and
are incorporated in this Item 4 in their entirety where such references and
descriptions appear.

Item 5. Interest in Securities of the Issuer.

     The information set forth or incorporated by reference in Items 3 and 4 is
hereby incorporated herein by reference.

     As a result of the Company Voting Agreements, SmartForce may be deemed to
be the beneficial owner of at least 3,177,361 shares of Centra Common Stock
which constitutes approximately 12.2% of the issued and outstanding shares of
Centra Common Stock based on the number of shares of Centra Common Stock
outstanding as of January 15, 2002, (as represented by Centra in the Merger
Agreement). SmartForce may be deemed to have the shared power to vote the shares
with respect to those matters described in Item 3, however, SmartForce (i) is
not entitled to any rights as a stockholder of Centra as to the above mentioned

                                                                             -2-



shares and (ii) disclaims any beneficial ownership of the shares of Centra
Common Stock which are covered by the Company Voting Agreements.

Set forth in Annex B are the names of the stockholders of Centra that have
entered into the Company Voting Agreements with SmartForce and their present
principal occupation or employment, including the name, principal business and
address of any corporation or other organization in which such employment is
conducted, to SmartForce's knowledge. Of the Centra stockholders that have
entered into the Company Voting Agreements, as of January 28, 2002, Messrs.
Navickas, Barrett, D'Amore and Hult have also executed the irrevocable proxy in
the form attached as Exhibit A to the Company Voting Agreement.

     Other than as set forth in this Schedule 13D, as of the date hereof (i)
neither SmartForce nor any subsidiary of SmartForce nor, to the best of
SmartForce's knowledge, any of SmartForce's executive officers, directors or
other affiliates beneficially owns any shares of Centra Common Stock, and (ii)
there have been no transactions in shares of Centra Common Stock effected during
the past 60 days by SmartForce or by any subsidiary of SmartForce or, to the
best of SmartForce's knowledge, by any of SmartForce's executive officers,
directors or other affiliates.

     References to, and descriptions of, the Merger Agreement and the form of
Company Voting Agreements as set forth above in this Item 5 are qualified in
their entirety by reference to the copies of the Merger Agreement and the form
of Company Voting Agreements listed as Exhibits 1 and 2 to this Schedule 13D,
and are incorporated in this Item 5 in their entirety where such references and
descriptions appear.

Item 6.   Contracts, Arrangements, Understandings or Relationships with Respect
          to Securities of the Issuer.

     The information set forth, or incorporated by reference, in Items 3 through
5 is hereby incorporated hereby by reference.

     In connection with the Merger Agreement, certain stockholders of Centra
(each an "Affiliate") have each entered into an affiliate agreement with
SmartForce (collectively, the "Affiliate Agreements") pursuant to which each
Affiliate has agreed not to sell, transfer, or otherwise dispose of any
SmartForce ADSs issued to such Affiliate in the Merger unless (i) such sale,
transfer or other disposition is made in conformity with the requirements of
Rule 145(d)(1) and, to the extent required by the terms of the Deposit Agreement
(as defined below), Rule 144(h), or (ii) such sale, transfer or other
disposition is made pursuant to an effective registration statement under the
Securities Act or an appropriate exemption from registration, or (iii) Affiliate
delivers to Parent a written opinion of counsel, reasonably acceptable to Parent
in form and substance, that such sale, transfer or other disposition is
otherwise exempt from registration under the Securities Act.

     References to, and descriptions of, the Affiliate Agreements as set forth
above in this Item 6 are qualified in their entirety by reference to the copies
of the form of Affiliate Agreement filed as Exhibit C to the Merger Agreement,
filed as Exhibit 1 to this Schedule 13D, and are incorporated in this Item 6 in
their entirety where such references and descriptions appear.

     References to, and descriptions of, the Merger Agreement and the form of
Company Voting Agreements as set forth above in this Item 6 are qualified in
their entirety by reference to the copies of the Merger Agreement and the form
of Company Voting Agreements listed as Exhibits 1 and 2 to this Schedule 13D,
and are incorporated in this Item 6 in their entirety where such references and
descriptions appear.

                                                                             -3-



  Item 7.      Material to be Filed as Exhibits.

  Exhibit   Description
  -------   -----------

     1.     Agreement and Plan of Merger and Reorganization, dated as of January
            16, 2002, by and among SmartForce PLC, Centra Software, Inc., and
            Atlantic Acquisition Corp., together with exhibits thereto.

     2.     Form of Voting Agreement, between SmartForce PLC and certain
            stockholders of Centra Software, Inc.

                                                                             -4-



                                    SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Dated: January 28, 2002
                                           SMARTFORCE PLC


                                           By:    /s/ David C. Drummond
                                                --------------------------------
                                           Name:  David C. Drummond
                                           Title: Executive Vice President of
                                                  Finance and Chief Financial
                                                  Officer

                                                                             -5-



                                                                         ANNEX A


     Set forth below is the name, citizenship, current business address, and the
present principal occupation or employment of each director and executive
officer of SmartForce PLC. Unless otherwise indicated, each person identified
below is employed by SmartForce PLC. The principal address of SmartForce PLC,
and unless otherwise indicated below, the current business address for each
individual listed below is 900 Chesapeake Drive, Redwood City, CA 94063.



   Name and Business Address                Present Principal Occupation or Employment         Citizenship
--------------------------------------     ----------------------------------------------     --------------
                                                                                         
Gregory M. Priest                           Chairman, Chief Executive Officer                  United States

David C. Drummond                           Executive Vice President, Chief Financial          United States
                                             Officer and Director

Thomas F. McKeagney                         Executive Vice President, Research and             Ireland
                                             Development

Jeffrey N. Newton                           Executive Vice President, Global Sales             United States

Ronald C. Conway                            Founder and Managing Partner, Angel                United States
   Angel Investors, L.P.                     Investors, L.P.
   76 Adam Way
   Atherton, CA 94027

John M. Grillos                             Chief Executive Officer, meVC Draper Fisher        United States
   meVC Draper Fisher Jurvetson Fund I       Jurvetson Fund I
   400 Seaport Court, #105
   Redwood City, CA 94063

Patrick J. McDonagh                         Chairman, Riverdeep Group PLC                      Ireland
   Riverdeep Interactive Learning Ltd.
   Styne House
   3rd Floor
   Upper Hatch Street
   Dublin 2
   Ireland

James S. Kryzwicki                          Senior Vice President and General Manager,         United States
   Divine, Inc.                              Enterprise Content, Divine, Inc.
   1301 North Elston Avenue
   Chicago, IL  60622

Ferdinand von-Prondzynski                   President, Dublin City University                  Ireland
   Dublin City University
   Dublin 9
   Ireland




                                                                         ANNEX B

Set forth below is the name, current business address, and the present principal
occupation or employment of each Centra Software, Inc. stockholder that entered
into a voting agreement with SmartForce PLC. Unless otherwise indicated, each
person identified below is employed by Centra Software, Inc. Except as indicated
below, the business address of each such person is c/o Centra Software, Inc.,
430 Bedford Street, Lexington, MA 02420.



                                                                                                      Shares
                                                                                                   Beneficially
     Name and Business Address              Present Principal Occupation or Employment                Owned
--------------------------------------    ------------------------------------------------        ---------------
                                                                                            
Leon Navickas                                 Chief Executive Officer and Chairman                   2,109,998

Stephen A. Johnson                            Chief Financial Officer and Treasurer                    154,684

Steven N. Lesser                              Senior Vice President, Worldwide Sales                   437,000

Joseph M. Gruttadauria                        Senior Vice President, Professional Services             323,130

David Barrett                                 General Partner, Polaris Venture Partners                 39,531
   Polaris Venture Partners
   1000 Winter Street
   Suite 3350
   Waltham, MA 02451

Richard D'Amore                               General Partner, North Bridge Venture                    103,018
   North Bridge Venture Partners                 Partners
   950 Winter Street
   Suite 4600
   Waltham, MA 02451

Robert E. Hult                                Senior Vice President Finance and Operations,             10,000
   NMS Communications Corp.                      Chief Financial Officer and Treasurer, NMS
   100 Crossing Boulevard                        Communications Corp.
   Framingham, MA 01702





                                  EXHIBIT INDEX

1.   Agreement and Plan of Merger and Reorganization, dated as of January 16,
     2002, by and among SmartForce PLC, Centra Software, Inc., and Atlantic
     Acquisition Corp., together with exhibits thereto.

2.   Form of Voting Agreement, between SmartForce PLC and certain stockholders
     of Centra Software, Inc.