The negative impact on psychologic adjustment from the stress of living with newly diagnosed cancer is hypothesized to be affected by perceived social support. Thirty children with newly diagnosed cancer completed standardized assessment instruments measuring depressive symptoms, state anxiety, trait anxiety, social anxiety, general self-esteem, and perceived social support from classmates, parents, teachers, and friends. Their parents completed a standardized assessment instrument measuring internalizing and externalizing behavior problems. Perceived classmate, parent, and teacher social support were variously correlated with the psychologic adjustment parameters in the hypothesized direction of greater support predicting lower psychologic distress and higher self-esteem. Hierarchical multiple regression analyses identified perceived classmate social support as the most consistent predictor of adaptation, providing further evidence of the essential function of the social environment of the school setting in affecting the adjustment of children with newly diagnosed cancer.J Dev Behav Pediatr 15:20-26, 1994