Plaintiffs' expert witnesses in EEO cases involving performance appraisals often claim that adverse impact is a result of the type of rating format used. Their theory is that more specific rating criteria will lead to lessened adverse impact. We tested that theory by comparing data from a simple category-based rating system against data from a standards-based Work Planning and Review appraisal system with over 248,000 performance appraisals of state employees. Using logistic regression and statistical definitions of prima facie discrimination, we found no support for the hypothesis that adverse impact is materially affected by criterion specificity. © 2003 Wiley Periodicals, Inc.