This article describes the origin, theoretical articulation, and decline of the theory of participatory democracy and makes a case for its revival, given its unique potential to illuminate recent empirical research on participatory democracy. Specifically, it is argued that while the theory of deliberative democracy is often described as “participatory,“ its primary focus on the mode of participation, namely deliberation among citizens, is overly narrow and fails to effectively address sectors of participation, namely the household, workplace, and the like. Because participatory democratic theory encompasses both modes and sectors of participation, the revival of participatory democratic theory will prove to be a more effective tool for revealing the strengths and weaknesses of actual participatory democracies. This article concludes by demonstrating how a revival of participatory democratic theory can illuminate the ongoing experiments in participatory democracy in Porto Alegre, Brazil, and moreover shows how those experiments can illustrate the strengths and weaknesses of participatory democratic theory and how the theory of participatory democracy can benefit from evidence from its practice.