Purpose: The purposes of this study were to: (a) meta-analyze the effects of academic press (AP) on K-12 student achievement in aggregate and in each examined learning subject; (b) meta-analyze the effect of school leadership of different leadership styles on AP; and (c) examine whether school level, subjects, and leadership or AP measures moderate these above-mentioned effects. Research Methods/Approach: Standard meta-analysis techniques were used to review 79 quantitative studies in the past 30 years and examine the multiple relationships between school leadership, AP, and student learning mentioned above. Heterogeneity analyses were conducted to identify moderators. Publication bias in these analysis results was also examined. Findings: AP had a large effect on student achievement; school leadership had a close to large effect on AP. These effects varied with leadership or AP measures and across school levels and student learning subjects. Implications for Research and Practice: The findings point to the importance of school leaders to improve student achievement by improving the level of AP in schools, especially high schools, and in schools with many economically disadvantaged students. Principals need to exercise a wide range of practices to push for academic excellence.