This article updates and describes a widely used data set on democracy. Covering 1800–2007 and 219 countries, it represents the most comprehensive dichotomous measure of democracy currently available. We argue that our measure’s distinguishing features—a concrete, dichotomous coding and a long time span—are of critical value to empirical work on democracy. Inspired by Robert Dahl, we define a country as democratic if it satisfies conditions for both contestation and participation. Specifically, democracies feature political leaders chosen through free and fair elections and satisfy a threshold value of suffrage. After comparing our coding to that of other popular measures, we illustrate how democracy’s predictive factors have evolved since 1800. In particular, we show that economic modernization variables have steadily declined in their correlation with democracy over time.