A longitudinal investigation was conducted to explicate how the confluence of early behavioral dispositions, relational histories, and cognitive representations of the self and others contributes to internalizing problems, externalizing problems, and loneliness. One-hundred and ninety three girls, and 206 boys were assessed annually from age 5 (kindergarten) to age 10 (Grade 4). Early aggressive behavior was related to Grade 4 maladjustment directly and indirectly through subsequent relational stressors. Significant associations emerged between chronic friendlessness and rejection and later adaptation not accounted for by concurrent relational difficulties. Self- and peer beliefs partially mediated the relation between peer difficulties and internalizing problems and loneliness. The results highlight the utility of child-by-environment models as a guide for the investigation of processes that antecede psychosocial maladjustment.