This investigation tested the person-by-environment hypothesis that the joint influence of behavioral vulnerability (anxious solitude) and interpersonal adversity (peer exclusion) predicts heightened social avoidance and depression over time. The study assessed 519 fifth and sixth graders 3 times during 1 year. Teachers reported social behavior and peer exclusion; youth reported depression. As hypothesized, anxious solitary youth displayed maintenance or exacerbation of social avoidance and depression in the context of high exclusion, but increased social approach and less depression in the context of low exclusion. Some effects were moderated by sex. The interaction of behavioral vulnerability and peer exclusion was more consistently linked to adjustment changes in anxious solitary youth than in youth with other behavioral profiles.