This study explored how nonpromotional school changes, a potentially major event for children, were associated with 3 forms of social maladjustment: isolation/withdrawal, affiliation with maladjusted peers, and aggression toward peers. Given that school mobility frequently co-occurs with family transitions, the moderating role of these transitions was investigated. These issues were examined in 2 longitudinal samples of U.S. (N = 1,364) and Canadian (N = 1,447) elementary school children. Propensity weighted analyses controlling for premobility individual, family, and friends' characteristics indicated that children who experienced both school and family transitions were at risk of either social withdrawal (in the Canadian sample) or affiliation with socially maladjusted peers (in the U.S. sample). These findings suggest the importance of considering both the social consequences of school mobility and the context in which such mobility occurs.