International research has shown that the quality of school leadership and management (SLM) is important for teaching and learning, particularly in schools where there is acute resource deprivation. This article explores the relationship between leadership and academic achievement in South African secondary schools with varying socio-economic conditions. The study is based on data from 12,154 South African Grade 9 learners, 334 mathematics teachers and 292 principals who participated in the 2015 Trends in International Mathematics and Science Study (TIMSS). Using indicators that represent different aspects of school leadership, this article examines whether the type of leadership and management practices depend on the school setting and whether better school leadership and management supports academic achievement. The analysis revealed distinct relationships between school leadership and management and academic achievement based on the socio-economic status of learner bodies. Potential policy responses are discussed.