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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 8-K
                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

          Date of Report (Date of earliest event reported): May 2, 2000

                                 S1 CORPORATION
             ------------------------------------------------------
             (Exact name of registrant as specified in its charter)




                  DELAWARE                                    000-24931                         58-2395199
        ----------------------------                        ------------                       --------------
                                                                                      
        (State or other jurisdiction                        (Commission                       (IRS Employer
              of incorporation)                             File Number)                    Identification No.)




3390 PEACHTREE ROAD, NE, SUITE 1700, ATLANTA, GEORGIA 30326
- -------------------------------------------------------------
       (Address of principal executive offices)

Registrant's telephone number, including area code: (404) 812-6200
                                                    --------------


                                 NOT APPLICABLE
          -------------------------------------------------------------
          (Former name or former address, if changed since last report)


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ITEM 5.  OTHER EVENTS.
         -------------
         On May 2, 2000, S1 Corporation ("S1") issued a press release
describing its results of operations for the first quarter of 2000. That press
release is filed as Exhibit 99.1 to this report. Also on May 2, 2000, S1 held an
analyst conference call during which S1 discussed its first quarter results and
presented certain other material relating to S1 and its operations. That
material is filed as Exhibit 99.2 to this report.

ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS.
         -----------------------------------
(a)      Not applicable.

(b)      Not applicable.

(c)      Exhibits.

         Exhibit
         No.               Description
         -------           -----------
         99.1              Press release, dated May 2, 2000.


         99.2              Materials presented during analyst conference call
                           held May 2, 2000.


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                                   SIGNATURES

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                    S1 CORPORATION
                                    --------------
                                    (Registrant)


                                    /s/ ROBERT F. STOCKWELL
                                    --------------------------
                                        Robert F. Stockwell
                                        Chief Financial Officer


Date: May 8, 2000


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                                  EXHIBIT INDEX

         Exhibit
         No.               Description
         -------           -----------
         99.1              Press release, dated May 2, 2000.


         99.2              Materials presented during analyst conference call
                           held May 2, 2000.