Our analysis finds no support for the idea that coups that end democracies or initiate new dictatorships are motivated by elite fears of popular opposition or redistribution. Instead, our results suggest that officers who seize political power are motivated by their own interests. Ethnic heterogeneity in the army is associated with more coups. Ethnic differences within the military predispose it to factionalism, and the grievances of one ethnic faction can motivate coups against dictatorships led by other ethnic factions. Coups are less likely to end democracies when the government includes representatives of all the country’s ethnic groups, implying that all ethnic groups represented in the officer corps are represented as well. A retest of existing arguments about the effect of income inequality on the likelihood of coups shows that earlier results depend on combining leader-shuffling coups with regime-change coups. When the two kinds of coups are examined separately, we find that middling levels of inequality are associated with leader-shuffling coups in on-going dictatorships, but not with coups that establish new dictatorships. Protest and civil conflict have no effect on the likelihood of regime-change coups.