On page 77, second line from the bottom of Brooks et al., “The Demographic Transition Theory of War: Why Young Societies Are Conflict Prone and Old Societies Are the Most Peaceful,” International Security, Vol. 43, No. 3 (Winter 2018/19), “total population” should be “adult population.” On page 78, figure 5, the caption “as a proportion of the total population” should be “as a proportion of the population aged 15 +.”