We combine Acemoglu and Robinson's model of the economic origins of democracy with Lohmann's model of political mass protest. This allows us to analyse the economic causes of political regime change based on the microfoundations of revolution. We are able to derive conditions under which democracy arises peacefully, when it occurs only after a revolution and when oligarchy persists. We model these possibilities in a world of asymmetric information, where information cascades are possible, and where these cascades may involve errors in the sense that they make everyone worse off.Why are some countries democratic and others not? Why do some countries have stable political institutions and others seem to be in a constant state of flux? And what role do economic factors play in determining a country's political institutions and their stability? These are difficult and important questions on which until comparatively recently economic theory was relatively mute. The current literature on the topic, like this article, is concerned primarily with the questions of whether and how societies will move from oligarchy to democracy.Two main themes pervade this literature; the first as in Acemoglu and Robinson (2000a, 2001, Conley and Temimi (2001), Overland et al. (2005) and Fender (2008, 2009) examines political and economic decisions when a ruling elite face a threat of revolution. Franchise extensions then arise as a means of removing this threat, by, for example, providing a credible commitment to redistribution. In this approach, the elite is homogeneous. In a second strand of literature, it is crucial that the elite is heterogeneous. Lizzeri and Persico (2004) and Llavador and Oxoby (2005) are examples of this genre; in Lizzeri and Persico, an elite may extend the franchise so as to avoid Pareto-inferior redistributive policies arising from internal political competition. In these split-elite setups, regime change does not require a threat of revolution.In both the split-elite and pre-existing revolutionary threat explanations of a transition to democracy, the transition itself is peaceful. Clearly, there are examples of such (relatively) peaceful democratic transitions, such as Britain in the nineteenth century, but there are numerous other examples where changes in the franchise only arose after bloody conflict; the French Revolution and its aftermath springs to mind as an obvious example. Indeed, why did Louis XVI not foresee the shadow of Madame Guillotine and behave accordingly? Although it is clearly implausible to hypothesise that all the events