Secondary analyses of the 1998 Canadian Incidence Study of Reported Child Maltreatment were carried out to investigate the effect of caregiver vulnerabilities on the substantiation of child abuse and neglect. Analyses were done of (1) demographic factors, socioeconomic disadvantage, and caregiver’s history of abuse; (2) caregiver vulnerability factors; (3) involvement in partner violence; and (4) the interaction between caregiver vulnerability and partner violence. Results showed that the total number of caregiver vulnerabilities was the best predictor of the substantiation of child abuse and neglect. Caregiver substance abuse was the single most important caregiver vulnerability in predicting maltreatment substantiation. High caregiver vulnerability and high partner violence increased the likelihood that maltreatment would be substantiated.