Evidence for resilience, competent functioning despite severe adversity, was investigated in school-age, disadvantaged maltreated (N = 127) and nonmaltreated (N = 79) children attending a summer camp program. Multiple areas of adaptation (social adjustment, risk for school difficulty, psychopathology) were assessed from self, peer, and camp counselor perspectives and school records. A composite index of adaptive functioning was developed, and levels of competence were delineated. Personality dimensions and personal resources, including cognitive maturity, self-esteem, ego-resiliency, and ego-control, were evaluated as mechanisms promoting individual differences in successful adaptation. Maltreated children as a group evidenced lower overall competence when compared to nonmaltreated children. An equal proportion of maltreated and nonmaltreated children, however, demonstrated high levels of competence, whereas more maltreated children than nonmaltreated children evidenced low levels of competence. Ego-resiliency, ego-control, and self-esteem were each found to predict individual differences in competent functioning. Evidence for the differential role of ego-control in promoting competence for maltreated versus nonmaltreated children was found. The results are discussed in terms of mechanisms contributing to resilient outcomes in maltreated children and the implications of the study of resilience for the field of developmental psychopathology. © 1993, Cambridge University Press. All rights reserved.