The authors analyze the correlations between students' time allocation and school performance in terms of grades and satisfaction with their own performance in math, German, first foreign language, and overall. They address the heterogeneity between three important extracurricular activities (student jobs, sports and music participation) and the heterogeneity within each activity by accounting for different types and participation length of an activity. The used cross-sectional survey data of 3388 students, who are about 17? years old and enrolled in a German secondary school, indeed reveal substantial heterogeneity between and within the activities. The empirical analysis is accompanied by an extensive survey of the empirical literature about the association between student jobs, sports, and music participation and school performance.