Samuel Huntington's (1991) thesis of democratic waves has come under strong criticism from scholars such as Renske Doorenspleet and Adam Przeworski and colleagues. We take issue with all of these authors' (including Huntington's) use of a dichotomous measure of democracy, which we believe creates the potential for inaccurate analysis of democracy and democratic/autocratic transitions. Using a more refined measure of democracy and of political system change we find substantial support for Huntington's wave thesis, and little support for the position of his critics who argue that there are no democratic waves. We proceed to locate the sources of the democratic waves. Reformulating and expanding on Huntington, we hypothesize that a combination of the `stickiness' of certain institutional configurations, the influence of neighboring countries, and shocks to the interstate system such as the world wars are the main explanation of waves, in combination with the slow but certain impact of economic development. Using multinomial logit analyses of political transitions, we find considerable support for these hypotheses.