The ABC of Gender Equality in Education: Aptitude, Behaviour, Confidence tries to determine why 15-year-old boys are more likely than girls, on average, to be overall low achievers, and why high-performing 15-year-old girls underachieve in mathematics, science and problem solving compared to high-achieving boys. As the evidence in the report makes clear, gender disparities in school performance stem from students’ attitudes towards learning and their behaviour in school, from how they choose to spend their leisure time, and from the confidence they have – or do not have – in their own abilities as students.