One of the most striking, and almost universal, educational trends of the last decade has been the shift in the relative achievements of males and females. In almost every OECD (Organisation for Economic Cooperation and Development) country, girls now do better than boys at almost every level, up to and including doctoral, and in almost every subject. In a few countries, maths, engineering and physics still remain a male preserve, but even in these the picture is changing. The author suggests that social capital may be the most valid explanation of the gender gap in educational attainment, and may also explain why women's educational achievements are not reflected in terms of pay and occupational status.