During adolescence, gender identity (GI) develops through a dialectic process of personal reflection and with input from the social environment. Peers play an important role in the socialization of gendered behavior, but no studies to-date have assessed peer influences on GI. Thus, the goal of the present study was to examine peer influences on four aspects of adolescents' GI in racially and ethnically diverse 7th- and 8th-grade students (N = 670; 49.5% boys, M age = 12.64) using a longitudinal social network modeling approach. We hypothesized stronger peer influence effects on between-gender dimensions of GI (intergroup bias and felt pressure for gender conformity) than on within-gender dimensions of GI (typicality and contentedness). Consistent with expectations, we found significant peer influence on between-gender components of GI--"intergroup bias" among 7th and 8th graders as well as "felt pressure for gender conformity" among 8th graders. In contrast, within-gender components of GI showed no evidence of peer influence. Importantly, these peer socialization effects were evident even when controlling for tendencies to select friends who were similar on gender, "gender typicality, and contentedness" (8th graders only). Employing longitudinal social network analyses provides insights into and clarity about the roles of peers in gender development.