Gender segregation in education is still prevalent in Western countries. It affects young people's further educational trajectories and occupational attainment and is thus closely linked with gender segregation in the labour market and social inequality. This contribution provides an overview of the main segregation patterns, theoretical explanations and consequences of educational gender segregation. We first outline how gender segregation in education has been conceptualised and measured and summarise the patterns of gender segregation in secondary and tertiary education. We then review the dominant theoretical explanations of gender segregation in education: as a result of future-oriented rational choices, of present-oriented gender identity expression, social approval and gatekeeping, and of past socialization of interests, values and perceived skills. Furthermore, macro-level opportunity structures, such as cultural value systems and the structure of the education system and the labour market are discussed. After reviewing research on the labour market consequences of gender segregation, the contribution concludes with a discussion of the main gaps in sociological segregation research.