This study examined the effectiveness of the First Step to Success (FSS) early intervention program designed to prevent antisocial behavior patterns of at-risk children who show early signs of these behaviors. Participants of the study included four Native-American students (two kindergarteners and two first-graders), their teachers, and their parents. The results indicated targeted students'' social play behaviors significantly increased while nonsocial play behaviors decreased following implementation of the program. Some positive changes in class-wide student behaviors and teacher behaviors were reported by the participant teachers. Also, two teachers rated the program as very effective, one teacher found it to be somewhat effective, and the fourth did not find it as effective. All teachers reported the program as easy to use. All but one participant parent reported significant changes in problem behaviors of targeted students. They all were highly satisfied with the program and rated it as easy to use.