Exhibit 23.1

                                                     [Grant Thornton Letterhead]

            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We have issued our reports dated March 3, 2006, accompanying the consolidated
financial statements and schedules, management's assessment of the effectiveness
of internal control over financial reporting and the effectiveness of internal
control over financial reporting included on the Form 10-K of SPSS Inc. for the
year ended December 31, 2005. We hereby consent to the incorporation by
reference of said reports in the Registration Statement of SPSS Inc. on this
Form S-8.


                                        /s/ GRANT THORNTON LLP

Chicago, Illinois
April 27, 2006