This study examines the social networks and deviant behavior of 92 male and female adolescent offenders in a secure training school. Semi-structured interviews were conducted individually with the youth and repeated following a four-week interval. Record data were reviewed to assess behavioral adjustment. The Social Cognitive Map analytic technique was utilized to identify social clusters. Findings indicate that these extremely delinquent youth formed reasonably stable social networks within the institution. Social clusters were distinguished most strongly on the basis of gender, race and proximity. Individuals within clusters had similar levels of behavioral adjustment and perceptions of intimacy with peers. The processes of peer group formation are similar to those found among public school counterparts. Treatment implications are discussed.Questions regarding the relationship between peer affiliations and deviant behavior have resulted in differing perspectives about the formation of deviant adolescent social groups. Particularly controversial has been the issue of whether or not juvenile delinquents are capable of forming relationships with others. In the criminological literature, control theory and the principle of differential associations provide contrasting views on how adolescent social relationships may enhance or inhibit deviant behavior. An alternative perspective has also been proposed by developmental psychologists. These contrasting viewpoints give rise to questions of whether deviant, aggressive behavior stems from an inability to form relationships with others and whether the formation of relationships is inhibitory to involvement in aggressive behavior. The present study examines peer group affiliations and deviant behavior in a secure setting for highly aggressive, delinquent adolescents. This investigation expands upon current research by utilizing concepts and