The purpose of the present research was to determine the similarities and differences between nondelinquent and delinquent youth, and to investigate the impact of family variables on delinquency. Based on a review of 285 records of institutionalized youth, patient demographic and developmental life history variables were examined. A stepwise discriminant analysis revealed that several variables distinguish between delinquent and nondelinquent adolescents. In comparison to nondelinquents, more delinquent youth were diagnosed as conduct disordered, had histories of prenatal complications, reached developmental milestones at unpredictable rates, performed poorly in school, experienced physical abuse, reported maternal psychopathologies, and were insecurely attached to both parents. These results are discussed and interpreted within the delinquency research.