This paper utilizes a national longitudinal probability sample of children to demonstrate how important exposure to multiple forms of victimization (polyvictimization) is in accounting for increases in children's symptomatic behavior. The study is based on two annual waves of the Developmental Victimization Survey that began with a nationally representative sample of children and youth ages 2 to 17. A broad range of victimization experiences were assessed using the 34-item Juvenile Victimization Questionnaire. Eighteen percent of the children experienced four or more different kinds of victimization (polyvictims) in the most recent year. Polyvictimization in the most recent year was highly predictive of trauma symptoms at the end of the year, controlling for prior victimization and prior mental health status. When polyvictimization was taken into account, it greatly reduced or eliminated the association between most other individual victimizations and symptomatology scores.