A review of 23 studies, including doctoral dissertations, statewide assessments, national surveys, journal articles, technical reports, books, and unpublished papers, sought to integrate empirical findings concerning the impact of leisure time television viewing on student achievement in grades K through 12. For each study, the reviewers coded the characteristics of the sample, type of outcome, quality of the study, method of collecting viewing data, mean hours of viewing, and strength and direction of observed relationships. A total of 274 effects were coded, converted to a common measure through techniques of research synthesis, and subjected to analysis of variance. Results indicate that the overall effect of hours of television viewing is negative, though small. Effects are slightly positive for up to ten hours of viewing a week, but become negative and increasingly deleterious for up to 35 or 40 hours a week. Females and children of high IQ are more adversely affected than other groups. An annotated bibliography and descriptive statistics are appended. (WD)