This study examined associations between multiple parental behaviors and children's participation in out-of-school math, science, and computer activities for children in 2nd (n = 125), 3rd (n = 123), and 5th grade (n = 200). Mothers and fathers reported how often they encouraged their children's activities, participated in activities with their child, provided activity-related materials, and participated in activities themselves, as well as how often their children participated in activities. The youth described how often they participated in math, science, and computer activities. Results indicate that parents' behavior is a strong, positive predictor of children's participation. Although there were significant mean level gender differences, relations between parents' behavior and children's participation were similar for boys and girls. (Contains 4 tables and 2 figures.)