Using a nationally representative sample of adolescents, we examine associations among social integration (network size), network cohesion (alter-density), perceptions of social relationships (e.g., social support) and adolescent depressive symptoms. We find that adolescents with either too large or too small a network have higher levels of depressive symptoms. Among girls, however, the ill effects of over-integration only occur at low levels of network cohesion. For boys, in contrast, the ill effects of over-integration only occur at high levels of network cohesion. Large social networks tend not to compromise positive perceptions of friend support or belonging; whereas, small networks are associated with low perceptions of friend support and belonging. Hence, perceptions of social relationships mediate the ill effects of under-integration, but not over-integration, on depressive symptoms. (Contains 1 note, 4 tables, and 2 figures.)