Objective: This study assessed the unique and interactive effects of child maltreatment and mothers' physical intimate partner violence (IPV) status on low-SES African American children's psychological functioning. Methods: Mothers were recruited from a large, inner-city hospital, and those who met eligibility criteria were asked to complete a lengthy face-to-face interview while their child was assessed separately but concurrently. The sample included 152 mother-child dyads. The children's mean age was 10 years, and 45% were male. Multivariate linear regression analyses tested the main and interactive effects of child maltreatment and mothers' exposure to physical IPV on children's psychological functioning (internalizing and externalizing symptoms, traumatic stress symptoms), while controlling for covariates. Results: Children who experienced child maltreatment and children whose mothers experienced physical IPV had higher levels of psychological distress than their respective counterparts. Post hoc analysis of significant interaction effects indicated that child maltreatment was associated with internalizing and externalizing problems and traumatic stress only when mothers reported higher levels of physical IPV. This finding did not hold true for youth whose mothers did not acknowledge elevated rates of physical IPV. Conclusions: African American youth from low-SES backgrounds who are maltreated and whose mothers experience physical IPV are at particularly high risk for psychological distress. Targeted prevention and intervention programs are needed for these poly-victimized youth. (Contains 3 tables.)