To explore predictors of adolescent participation in structured out-of-school activities, various types of structured out-of-school time use and their correlates were examined among 454 adolescents in Grades 9-12 in a rural southeastern state. Using a developmental-ecological model as an organizing framework, four different uses of time were explored with regard to self, family, and friend systems. Regression analyses revealed that time in after-school extracurricular activities was predicted by parent endorsement of activities, ethnicity, and friend endorsement of activities, whereas time spent in nonschool clubs was predicted by peer pressure, parent endorsement, and grades. Socioeconomic status, parental monitoring of activities, school grade level, and family structure predicted time spent in volunteering, and time spent in religious-related activities was predicted by ethnicity, family structure, friend endorsement, and gender.