The present study examined changes in nonsocial play (reticent behavior, solitary-passive behavior, and solitary-active behavior) and the relations between nonsocial play and social skills and problem behavior for boys (N = 50) and girls (N = 35) in 2-year-course kindergartens. Children's nonsocial play was observed immediately upon their entering kindergarten (Time 1) and 6 months later (Time 2). Their social skills and problem behavior were rated by their teachers at Time 1, Time 2, and just before graduation (Time 3). The results revealed that the rate of reticent behavior decreased from Time 1 to Time 2. Reticent behavior was negatively related to assertive skills in both the boys and the girls. Solitary-passive behavior at Time 2 was related to low cooperative skills and high carelessness/hyperactivity for the girls, and predicted low assertive skills at Time 3 for the boys. There were no significant relationships to solitary-active behavior at the same point in time. However, one of them at Time 1 predicted subsequent low assertive skills for the boys, and one at Time 2 predicted externalizing problem behavior at Time 3 for the girls.