Recent research documents both the influence of social networks on adolescent depression and the influence of depression on the structure of adolescent friendship networks. Considerable research also documents gender differences on fundamental network processes. The present research examines the somewhat surprising implications of this classic gendered pattern of friendship structures for studying depression homogeneity among boys and girls. I propose that in girls’ friendship networks, where the network is compartmentalized into micro-structures, the tendency of depressed adolescents to withdraw from interaction, while effectively insulating the rest of the group from contagion, also isolates depressed girls from potential social support. In contrast, boys’ denser and more inclusive friendship networks may offer more opportunities for depression transmission through peer influence, resulting in contagion-based homophily. Using stochastic actor-based models in a meta-analysis of 421 adolescents from mixed-gender, all-girl, and all-boy classrooms in six Taiwanese high schools, I find predicted friendship network structures in girls’ and boys’ classrooms. Moreover, when controlling for the reciprocal effects of network dynamics and depression change, results suggest that social withdrawal of depressed girls explains depression homophily in both single-gender and mixed-gender classrooms, while peer influence predicts depression homophily in all-boy classrooms.