Chapter 9 focuses on succession, asking why some polities have institutionalized the process of leadership succession, while others have not. We argue that leadership succession is conditioned by (among other things) the size of a polity, with larger communities experiencing more frequent, and more regular, succession. As we discuss in the theoretical section, this is because larger polities are less cohesive, generating a greater number of veto holders. With more veto holders, the ruler will find it more difficult to hold on to power indefinitely and to pass on power to heirs. Since no extant work – at least, no work that we are aware of – is devoted to the influence of scale on leadership succession in a polity’s top office, we exclusively draw on our own analyses. We examine the question empirically using three measures of succession to the top political office: tenure in office, monarchy, and a composite index of institutionalized leadership succession. We find that tenure is shorter among leaders of larger countries, monarchs are much more likely to rule over smaller countries, and institutionalized leadership succession is inversely correlated with the size of a country.