Multivariate analyses are used to determine how these factors correlate with the results of competence tests in mathematics and German and teachers’ assessments of children’s social skills and concentration. The data stem from responses by and on fourth-graders to the National Education Panel Study (NEPS). The results show that sporting and musical activities correlate positively with the children's level of performance in German and mathematics. Similarly, moderate media use with up to two hours of media consumption per day is positively related to social skills and the ability to concentrate. Taking all these different aspects of children's living conditions together, it is clear that compared with leisure activities the influence of other factors, such as family structure, parental employment and migrant background, is secondary. The message for policymakers is that they should work on providing all children with leisure activities which promote their competence development. This means, on the one hand, further expanding the services offered by childcare facilities and all-day schools and, on the other, establishing counselling services aimed specifically at parents.