Steps in a class action suit charging prejudicial treatment of a minority group by a college or university are summarized, and attention is directed to how the plaintiffs can use the institution's own data to establish a prima facie case for disparate treatment. The key legal issues are indicated, and typical data and statistical exhibits that an institution might expect to see filed against them by the plaintiffs are displayed. Emphasis is placed on the role institutional researchers play in the defense phase, particularly with regard to strategies for defending against a multivariant regression model that the claimant's statistical expert has submitted in evidence of a classwide bias. The overall class of women faculty members is used as an example of a class action suit. After certification of the class, which may take two or three years, the exact nature of the alleged discrimination against specific individuals is investigated. The length of the second phase is largely dependent upon the number of class members who come forward with claims of discriminatory injury. One type of claim, called the disparate impact doctrine, asserts that the selection process used for determining salaries and promotions had had a substantial disproportionate and unfavorable impact on the class. The second type of claim, called the disparate treatment doctrine, asserts that the selection procedure is intentionally discriminatory. The literature of courtroom use of regression models suggests that both sides need to produce explanatory models. In some cases a prehearing protocol has been developed to specify those data variables that are relevant and important and to ensure that both sides begin with those data. Among the suggestions offered to institutional researchers are to become familiar with regression studies, and to have institutional studies on faculty available for reference. A bibliography is appended. (SW)