School motivation and attachment typically decline after the transition to middle school. According to the stage–environment fit approach, extracurricular activities are supposed to promote motivation. However, research has shown that the effects depend on the quality of the activities, which usually is measured by assessing students’ individual perceptions. This article adds to previous studies in examining effects of school-based extracurricular participation on the development of individual motivation (learning goal orientation) and school attachment depending on the quality of the activities (i.e., amounts of challenge and social support) at the school level. We focused on the motivation development of 3,230 students at 98 schools who filled in questionnaires in Grades 5 (2005), 7 (2007), and 9 (2009). The quality of extracurricular activities was assessed on the basis of responses from 4,270 students in Grades 5, 7, and 9 at the same schools at the first measurement point (2005). Thus, individual development of the longitudinal sample was predicted by aggregated quality measures at the school level. Three-level hierarchical linear growth-curve models including school level, student level, and time were calculated. Cross-level interactions were analyzed to examine the influence of extracurricular participation on individual development as a function of school quality. Results show that the effects of extracurricular participation on the development of learning goal orientation are dependent on both features of school quality, whereas the development of school attachment in particular is influenced by activities offering social support. Thus, the effects of extracurricular activities are based not only on individual perceptions of activity features but also on school quality.