An enduring puzzle in the study of revolutions is why some produce dictatorship and others democracy. Selectorate theory offers a parsimonious answer arguing that the incentives leaders face in the struggle for political survival shape the decisions they make on postrevolutionary institutional forms. The theory contends that only the scale of victory and its attribution help us understand revolutionary outcomes. However, we argue that ideology, specified as a consistent and explicit vision for a future polity, has been improperly discounted. Ideological commitments by revolutionary challengers made prior to the onset of a revolutionary situation influence the formation of challenger coalitions, increase the odds of victory, and subsequently constrain the range of choices available to winners by limiting plausible coalition partners, informing allocation decisions, and defining the acceptable scale and attribution of victory. We use historical case studies for theory building, allowing us to illustrate mechanisms and assess the theory's internal validity. The cases demonstrate why ideological commitments have been crucial factors not only affecting the political survival of political leaders, but also the institutions that developed out of revolutions.