Previous research has suggested that volunteering may have beneficial developmental consequences for adolescents. However, the sparse research on youth volunteerism is generally limited by a cross-sectional design that does not elucidate causal relations. This study addresses the questions, "Who participates in volunteer work?" and "What are the effects of youth volunteerism?" A panel study of a representative community sample of both volunteers and nonvolunteers indicates that those adolescents who become involved in volunteer activities have higher educational plans and aspirations, higher grade point averages, higher academic self-esteem, and a higher intrinsic motivation toward school work. But irrespective of these bases of selection, there is evidence that volunteering affects important work-related and social outcomes. Volunteering is found to strengthen intrinsic work values and the anticipated importance of community involvement and to decrease the anticipated importance of career.