This paper provides the first nationwide evidence on the long-term mental health effects of childhood exposure to civil conflict. I examine the impact of exposure to the 1996–2006 Nepali civil conflict on clinically validated measures of anxiety and depression, using data on the timing and location of all conflict-related casualties combined with the 2022 Nepal Demographic and Health Survey. Exploiting variation in conflict intensity by village and year of birth, I find that exposure in utero and up to age six increases the risk of anxiety in adulthood. Additionally, exposure at ages four to six raises the risk of depression in adulthood. These findings are robust to the inclusion of district-level trends, additional covariates and alternative measures of conflict exposure. While conflict exposure increases the likelihood of receiving counselling for a mental health condition, I find no significant effects on the probability of diagnosis or medication use for anxiety or depression, suggesting unmet need for mental healthcare services.