The presence of an exceptionally large youth population, that is, a youth bulge, is often associated with an elevated risk of civil conflict. In this article, we develop an instrumental variable approach in which the size of the youth cohorts in Sub-Saharan Africa is identified using variation in birth-year drought incidence. Our results show that an increase in the size of the population group aged fifteen to nineteen raises the risk of low-intensity conflict. A 1 percent increase in the size of this age-group augments the likelihood of civil conflict incidence (onset) by 2.3 (1.2) percentage points. On the other hand, we do not find any association between the size of the two adjacent youth cohorts, that is, the population groups aged ten to fourteen and twenty to twenty-four.