Research suggests that many typically developing children in the United States experience problems during the transition from preschool to kindergarten. Despite the fact that early school experiences impact educational trajectories, few empirical studies investigate the effect of kindergarten preparation variables on child outcomes. The primary purpose of this study was to investigate the relation between kindergarten preparation variables, including early education experiences and family involvement in preparation activities, and children's socio-behavioral outcomes in kindergarten. Participants included 86 general education students, their parents, and teachers. Data collection involved parent reports of child and family demographic information and behavioral involvement in kindergarten preparation activities as well as assessment of teacher-reported child outcomes, including student-teacher relationships, social skills, and problem behavior. Kindergarten preparation variables, particularly early education experience, significantly predicted kindergarten student-teacher relationship quality and school problem behavior, after accounting for the effects of district locale, family socio-economic status, and parent-reported problem behavior. The importance of preparation activities for supporting child socio-behavioral adjustment in kindergarten is discussed.