We examined the associations among gender, antisocial behavior, and peer-group affiliation in a high-risk sample of 401 homeless and matched housed adolescents (139 boys and 262 girls). The Diagnostic Interview Schedule for Children (Version 2.3, 1991; Costello, Edelbrock, Kalas, Kessler, & Klaric, 1982) yielded 2 measures of adolescent antisocial behavior: symptoms of conduct disorder and substance abuse or dependence. Various deviant behaviors of friends were assessed based on adolescent self-report. Results indicated that, for both boys and girls, having many deviant peers was associated with more antisocial behavior, regardless of the number of boys in the peer network. Furthermore, findings suggest that the relation between number of deviant peers and antisocial behavior may be stronger for boys and homeless adolescents than for girls and housed adolescents, respectively. The results of prior studies indicating that antisocial behavior is a function of affiliation with male peers may be due to the higher frequencies of maladaptive behaviors evidenced in boys in normative samples.