Practice is defined as experience with a test. The practice effect in test taking is an advantage in test performance that results from previous experience with the same form or a parallel form of a test. Unlike coaching, no other instruction, interpretation, or help is involved. Eight British studies, of particular interest because of their competitive admission to grammar school, were reviewed. Nine American studies were also reviewed, involving intelligence tests, the Scholastic Aptitude Test, and the Test of General Educational Development. Of these seventeen studies, eight interpreted the findings statistically. Of these, a significant practice effect was found in three studies, no significant effect was found in three, and two studies showed mixed results. It was concluded that practice improved performance on intelligence and scholastic aptitude tests. The effects of a first and second practice were significant; thereafter the effect diminished. Practice effects varied with the time interval between practice and final tests; significant practice effects were demonstrated for time intervals of two weeks to three months. Practice effect interacted with mental ability; the most intelligent students appeared to benefit the most.