Understanding what factors influence positive youth development has been advocated by youth development researchers (P. L. Benson, 2006; J. S. Eccles & J. A. Gootman, 2002). Consequently, the purpose of this study was to examine whether perceptions of a caring youth sport context influenced prosocial and antisocial behavior through efficacy-related beliefs, that is, positive and negative affective self-regulatory efficacy (ASRE) and empathic self-efficacy (ESE). Multiethnic youths taking part in summer sport programs (N = 395) completed a questionnaire that measured perceptions of the caring climate, ESE, ASRE, and social behavior. Structural equation modeling was used to test whether ASRE and ESE mediated the relationship between caring and social behaviors. Findings revealed that perceptions of caring positively predicted ASRE and ESE. In turn, positive ASRE positively predicted ESE. Prosocial behaviors were positively linked to ESE, whereas antisocial behaviors were negatively predicted by positive ASRE. The results suggest that caring influences prosocial and antisocial behavior because such contexts develop youths' ability to monitor, manage, and control positive affect, which in turn enhances their belief in their ability to empathize. (Contains 2 footnotes, 1 table, and 4 figures)