This study re-examines the empirical support for one of the most influential explanations of leadership tenure, “selectorate theory,” by testing for consistency across key regime categories. The argument made herein is that if the measures are good, the consistency of their relationships should not be limited to particular nominal regime categories, and they should capture the implications of the theory differentiating it from competing theories. Current measures of selectorate theory concepts are wanting on both fronts. I find that the measure used for winning coalition size is correlated with the destabilization of leaders in democracies and the stabilization of leaders in nondemocracies. I also find that the measure of selectorate size exhibits two behaviors inconsistent with the theory: larger selectorates are only stabilizing after the leader has already been in office for an extended period of time; and the effect is only substantial for differentiating between types of military regimes. These findings have five implications: (1) they cast serious doubt on the utility of current measures of selectorate theory; (2) they raise conceptual questions about the treatment of political regimes as vectors or categories; (3) they define substantive, not just statistical, issues that future measures will need to address; (4) they give baselines for re-analysis of the effect of these measures on other implications of interest; and (5) they provide an interesting comment on the comparative politics literature on hybrid regimes and the effect of parliamentary institutions in nondemocratic regimes.