ABSTRACT: This study analyzed and synthesized findings from selected studies conducted from 1960 through 1997 regarding effects of school sexuality education on adolescents' sexual knowledge. This purpose was achieved using meta-analysis. Sixty-seven studies that met the selection criteria were included in the meta-analysis. The 67 studies reported 72 outcomes regarding sexual knowledge, which were grouped into six independent variables related to knowledge about sexuality. A weighted effect size method developed by Hedges and Olkin was calculated using all studies. For all studies, 97% of weighted effect sizes were positive. The weighted average effect size on sexual knowledge across all studies of 0.41 was statistically significant, indicating a significant difference occurred between control and experimental groups' mastery of objectives related to sexual knowledge. It was concluded that sexuality education programs positively affect overall sexual knowledge.