The present study aims to generate broad insights from the large corpus of literature on the associations between a comprehensive range of school leadership practices and student outcomes in different school contexts. Three-level meta-analysis of 493 independent effects from 108 studies published since 2000 showed that the mean effect size was small at r = 0.14. Effect sizes for leadership practices ranged from r's = 0.10 to 0.26. Results underscored the importance of different types of leadership practices related to instructional management, enhancing teacher capacity, and engaging external stakeholders to improve student outcomes. School leadership practices were significantly associated with students' academic achievement (in different subjects except science) and learning attitudes/processes but not attainment. Moderator analyses showed that school leadership effects were significant in studies using a school-level analysis but not in those using a lower-level of analysis. Additionally, school leadership effects were significant at different grade levels (G1-G6, G7-G12) and in research reported in different study types (articles, dissertations) and in different years (2000-2009, 2010-2018).