Despite extensive literatures on the impact on children of exposure to violence in families, neighborhoods, and peer groups, there has been relatively little effort evaluating their cumulative impact. There also has been less attention to the effects of exposure to political conflict and violence. We collected data from a representative sample of 600 Palestinian youths (3 age cohorts: 8, 11, and 14 years old) to evaluate the relation of exposure to political conflict and violence, and violence in the family, community, and school, to posttraumatic stress (PTS) symptoms and aggressive behavior. Results highlight the additive effects of exposure to political conflict and violence, suggesting that interventionists should consider the full spectrum of sources of environmental risk for PTS symptoms and aggressive behavior. (Contains 2 footnotes and 4 tables.)