This research examines how family dynamics like interparental conflict, family violence, and quality of parenting are associated with young children's experiences of sibling victimization. We use nationally representative data from interviews with caregivers of 1,726 children aged 2 to 9 years of age. We hypothesized different family dynamics predictors for a composite of common types of sibling victimization (property, psychological, and mild physical aggression) in comparison to severe physical sibling victimization (victimization that includes physical aggression with a weapon and/or injury). Multinomial regression results showed that sibling victimization in general was associated with negative family dynamics but that children in the severe group had even less parental warmth, poor parental supervision, and greater exposure to interparental conflict and family violence than children in the common types victimization group. Different aspects of family dynamics contribute to sibling victimization, but possibly in different ways and with different consequences. The findings underscore the importance of a family systems theory approach to clinical and intervention work.