Aggregated data meta-analyses indicate a correlation between instructional leadership and student achievement. However, it is unclear to what extent this relationship can be generalized across cultural contexts, as most primary studies stem from Anglophone regions. Drawing on international large-scale assessment data, this 3-level individual participant data (IPD) meta-analysis examines this relationship over a 6-year period using a sample of 1.5 million students in more than 50,000 schools from 75 countries. The findings show that the mean correlation is close to 0 and that the relationship between instructional leadership and student achievement varies significantly across contexts. This is mainly due to the level of human development and cultural factors. Implications for policy, practice, and education research are discussed.