This paper provides causal evidence on early-life exposure to war on mental health status in adulthood. Using an instrumental variable strategy, the evidence indicates that early-life exposure to bombing during the American war in Vietnam has long-term effects. A one percent increase in bombing intensity during 1965–75 increases the likelihood of severe mental distress in adulthood by 16 percentage points (or approximately 50 percent of the mean) and this result is robust to a variety of sensitivity checks. The negative effects of war are similar for both men and women. These findings add to the evidence on the enduring consequences of conflict and identify a critical area for policy intervention.