Previous studies indicate that as many as 25-50% of applicants in organizational and educational settings are retested with measures of cognitive ability. Researchers have shown that practice effects are found across measurement occasions such that scores improve when these applicants retest. This study uses meta-analysis to summarize the results of 50 studies of practice effects for tests of cognitive ability. Results from 107 samples and 134,436 participants revealed an adjusted overall effect size of .26. Moderator analyses indicated that effects were larger when practice was accompanied by test coaching, and when identical forms were used. Additional research is needed to understand the impact of retesting on the validity inferences drawn from test scores.