This quantitative study examines patterns of participation in different afterschool settings over a 2-year period among ethnically diverse, low-income children and early adolescents (N = 2,914; 53% female; 66% Latine, 10% Black; Mchildren's age = 8.7 years, Mearly adolescents' age = 11.7 years). Four reliable patterns were found: (a) afterschool programs plus extracurricular activities, (b) afterschool programs plus extracurricular activities and unsupervised time, (c) mainly unsupervised, and (d) supervised informal. Patterns with more unsupervised time were more common among early adolescents than children. Both children and early adolescents in the Program + Activities group showed significant gains in work habits, task persistence, and prosocial behaviors, whereas youth in the Program + Activities & Unsupervised group did not differ from the Mainly Unsupervised group. These findings indicate that participating in afterschool programs and extracurricular activities can benefit ethnically diverse youth, but not when they co-occur with elevated unsupervised time.