The principle focus of this article is to understand the influence of socialisation in the family on the success of girls at school. Eight low-income families with children of both sexes in the city of São Paulo, Brazil were studied through interviews and observation methods. It was found that socialisation in the family favoured in girls, and not in boys, the development of behaviours that schools desire, such as discipline. It also led each sex to attribute a different meaning to school attendance, since girls had more responsibilities and fewer opportunities for socialising. The same restrictions prompted girls to aspire to further their education and have higher skilled occupations.