FIRST AMENDMENT TO PARTICIPATION AGREEMENT

         THIS FIRST AMENDMENT TO  PARTICIPATION  AGREEMENT  (this  "Amendment"),
dated as of April 5, 1999, is entered into by and among:

                  (1) FAIR,  ISAAC AND  COMPANY,  INC.,  a Delaware  corporation
         ("Lessee");

                  (2) LEASE PLAN NORTH  AMERICA,  INC., an Illinois  corporation
         ("Lessor");

                  (3) Each of the financial institutions listed in Schedule I to
         the   Participation   Agreement   referred   to  in   Recital  A  below
         (collectively, the "Participants"); and

                  (4) ABN AMRO BANK,  N.V.,  acting  through  its San  Francisco
         International  Branch, as agent for the Participants (in such capacity,
         "Agent").


                                    RECITALS

         A.  Lessee,  Lessor,  the  Participants  and  Agent  are  parties  to a
Participation   Agreement   dated  as  of  May  15,  1998  (the   "Participation
Agreement").

         B. Lessee has requested Lessor, the Participants and Agent to amend the
Participation  Agreement to change the covenant limiting Lessee's  repurchase of
its Equity Securities.

         C.  Lessor,  the  Participants  and Agent are  willing  so to amend the
Participation  Agreement  upon the terms and subject to the conditions set forth
below.


                                    AGREEMENT

         NOW,  THEREFORE,  in  consideration of the above recitals and for other
good and  valuable  consideration,  the receipt and adequacy of which are hereby
acknowledged,  Lessee,  Lessor,  the  Participants  and  Agent  hereby  agree as
follows:

         1. Definitions, Interpretation. All capitalized terms defined above and
elsewhere in this Amendment shall be used herein as so defined. Unless otherwise
defined  herein,  all  other  capitalized  terms  used  herein  shall  have  the
respective  meanings  given to those terms in the  Participation  Agreement,  as
amended by this Amendment.  The rules of construction set forth in Schedule 1.02
to the  Participation  Agreement shall, to the extent not inconsistent  with the
terms of this Amendment,  apply to this Amendment and are hereby incorporated by
reference.

         2. Amendment to Participation Agreement. Subject to the satisfaction of
the  conditions  set forth in Paragraph 4 below,  Clause  (iii) of  Subparagraph
5.02(f)  of the  Participation  Agreement  is hereby  amended to read in full as
follows:

                                                                   EXHIBIT 10.19




                  (iii) Lessee may  repurchase its Equity  Securities,  provided
         that the cost of any such repurchase,  when added to the aggregate cost
         of all other  repurchases  made pursuant to this clause (iii) since the
         date of this  Agreement,  does not exceed the greater of $25 million or
         five percent (5%) of Lessee's Tangible Net Worth on the last day of the
         immediately preceding fiscal year.

         3.  Representations  and  Warranties.   Lessee  hereby  represents  and
warrants to Agent and the  Participants  that the following are true and correct
on the date of this Amendment and that, after giving effect to the amendment set
forth in  Paragraph  2 above,  the  following  will be true and  correct  on the
Effective Date (as defined below):

                  (a) The  representations and warranties of Lessee set forth in
         Paragraph  4.01  of  the  Participation  Agreement  and  in  the  other
         Operative Documents are true and correct in all material respects as if
         made on such date (except for representations and warranties  expressly
         made as of a specified date, which shall be true as of such date);

                  (b) No Default has occurred and is continuing; and

                  (c)  All of the  Operative  Documents  are in full  force  and
         effect.

(Without limiting the scope of the term "Operative  Documents," Lessee expressly
acknowledges  in making the  representations  and  warranties  set forth in this
Paragraph  3 that,  on and  after  the date  hereof,  such  term  includes  this
Amendment.)

         4. Effective  Date. The amendments  effected by Paragraph 2 above shall
become effective April, 5, 1999 (the "Effective Date") so long as Lessor,  Agent
and the  Participants  have  received  on or prior to the  effective  Date  this
Amendment duly executed by Lessor, Lessee, each Participant and Agent.

         5. Effect of this  Amendment.  On and after the  Effective  Date,  each
reference in the  Participation  Agreement and the other Operative  Documents to
the Participation  Agreement shall mean the  Participation  Agreement as amended
hereby.  Except as specifically  amended above, (a) the Participation  Agreement
and the other Operative  Documents shall remain in full force and effect and are
hereby ratified and affirmed and (b) the execution,  delivery and  effectiveness
of this Amendment shall not, except as expressly  provided herein,  operate as a
waiver  of any  right,  power,  or  remedy of the  Participants  or  Agent,  nor
constitute a waiver of any provision of the Participation Agreement or any other
Operative Document.

         6. Miscellaneous.

                  (a) Counterparts. This Amendment may be executed in any number
         of identical  counterparts,  any set of which signed by all the parties
         hereto shall be deemed to constitute a complete,  executed original for
         all purposes.

                  (b) Headings.  Headings in this Amendment are for  convenience
         of  reference  only  and are  not  part of the  substance  hereof.

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                  (c)  Governing  Law. This  Amendment  shall be governed by and
         construed  in  accordance  with  the laws of the  State  of  California
         without reference to conflicts of law rules.


                            [Signature pages follow]

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         IN WITNESS WHEREOF,  Lessee,  Lessor,  Agent and the Participants  have
caused this Amendment to be executed as of the day and year first above written.


LESSEE:                                FAIR, ISAAC AND COMPANY, INC.


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________



LESSOR:                                LEASE PLAN NORTH AMERICA, INC.


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________



AGENT:                                 ABN AMRO BANK N.V.


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________


PARTICIPANTS:                          ABN AMRO BANK N.V.


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________

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                                       KEYBANK NATIONAL ASSOCIATION


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________


                                       BANQUE NATIONALE de PARIS


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________



                                       FLEET NATIONAL BANK


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________



                                       THE DAI-ICHI KANGO BANK, LIMITED
                                            Los Angeles Agency


                                       By: _____________________________________
                                           Name: _______________________________
                                           Title: ______________________________

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