OBJECTIVE: To examine the co-occurrence of witnessing partner violence with child maltreatment and other forms of victimization. METHOD: Data are from the National Survey of Children's Exposure to Violence (NatSCEV), a nationally representative telephone survey of the victimization experiences of 4,549 youth aged 0-17. RESULTS: Witnessing partner violence (WPV) is very closely associated with several forms of maltreatment and exposure to other forms of family violence in this sample, with adjusted OR ranging from 3.88 to 9.15. WPV is also significantly associated with a wide variety of other forms of victimization, with OR ranging from 1.43 to 7.32. More than 1/3 (33.9%) of youth who witnessed partner violence had also been maltreated in the past year, compared with 8.6% of non-witnesses. For lifetime data, more than half (56.8%) of WPV youth had also been maltreated. Neglect and custodial interference were most closely associated with WPV. CONCLUSIONS: These data support the poly-victimization model, indicating that many youth experience multiple forms of victimization. They also indicate that the various forms of family violence are especially closely linked. PRACTICE IMPLICATIONS: These results provide new urgency to calls to better integrate services to adult and child victims of family violence. For example, screening to identify the needs of child witnesses could be done in domestic violence shelters, and screening to identify the needs of adult victims could be done in child protective service settings.