A quantitative method, meta-analysis, is used to integrate research findings from a representative group of 38 coaching studies. Because different studies reported results on different scales, effect size was used to transform all results to a common metric. This meta-analysis showed that there are two distinct literatures on the effectiveness of coaching programs. The first is on the Scholastic Aptitude Test (SAT), and reports small effects from coaching. The second covers other aptitude tests and shows that coaching programs can have substantial effects. Studies that used a pretest yielded larger estimates of pure coaching effects than did other studies. This indicates that a pretest may be an important component in any program designed to prepare students for aptitude tests. Results support the conclusion that variation in study findings is only modestly predictable from study characteristics. (PN)