The increased prevalence and seriousness of antisocial behavior displayed by today's youths have become serious concerns for parents, educators, and community members. Antisocial behavior has a developmental course that starts with minor offenses in preschool (e.g., whining, teasing, noncompliance) and develops into major offenses (e.g., vandalism, stealing, assault, homicide) in older children and adolescents. Research results suggest that if interventions are implemented in the early elementary years, the likelihood of preventing future antisocial behavior is improved. Furthermore, interventions are said to be more successful if family members and teachers are involved. The purpose of this study was to examine the effects of an early intervention strategy, First Step to Success, involving (a) teacher-directed and (b) a combination of teacher- and parent-directed strategies on the behaviors of elementary school children at risk for antisocial behavior. The results suggest that interventions involving teachers and parents were associated with decreases in problem behavior in the classroom that maintained over 1 academic school year after intervention. Implications and recommendations are presented based on the outcomes and limitations of the study. (Contains 4 tables and 6 figures.)