Research finds differences between girls and boys in pathways to drug abuse, but few studies explore whether gender differences affect treatment response. The relational perspective of deviant behavior posits that adolescent female delinquency is likely to be more strongly influenced by problems with family and peer relationships than is adolescent male delinquency. This study explored the utility of the relationality perspective in explaining how criminally involved adolescent male and female drug users respond to peer-oriented treatment components as implemented in one program. Data were from a quantitative study of 449 criminally involved adolescents mandated to residential treatment programs, and 30 semi-structured interviews with a similar group of 7 boys and 3 girls attending a residential treatment program. The results showed that girls engaged in relationship building, but it was predominantly on a sexual level with boys and appeared to fulfill their instrumental needs as much as or more than their relational or intimacy needs. Girls were more likely than boys to have lived with a sexual partner in the year prior to treatment entry and were also more likely to have bought from and used with a sexual partner. They reported less satisfaction with their sexual relationships and less overall social support than boys. Girls described their pretreatment relationships with much older males as providing needs-based support (money, clothes, protection), not emotional support. The relational perspective failed to address the difficulty the girls reported in developing same-sex friendships. The girls interviewed expressed distrust and dislike of other girls and did not initially respond well to the same-sex peer component of this program. Relationality as it has been applied to explain gender differences in substance abuse behavior must be conceived as a complex concept requiring further elaboration. 2 tables, 56 references