This book gathers a series of studies by scholars who have dedicated these last few years to research in the field of participatory democracy. Their purpose is precisely to engage in a theoretical discussion about the value of participatory democracy in the 21st century. Part I deals with the challenge of antipolitics. This is one of the greatest challenges faced by contemporary democratic theory: How can it be possible to take into account in political decision-making processes those whose voices issue disagreement with the available alternatives in the exact same political decision-making processes, without simply excluding them provisionally from democratic participation? Part II focuses on challenges to deliberative systems. Deliberative democracy is probably the most important alternative conception of democracy in today's available literature on the topic, insofar as it responds to a sort of general uneasiness with mere preference aggregation by majoritarian voting, and instead seeks to incorporate the vast spectrum of heterogeneous interests in modern societies in the search for mutually acceptable policies. However, it is also subject to specific theoretical challenges that must be overcome if it is to be taken seriously as a viable alternative for providing better conditions of political participation. Part II deals with some of those challenges, even if in a sympathetic attitude towards deliberative decision-making. Finally, Part III approaches pluralism and cultural diversity in a shared public space. Its main challenge consists in promoting an idea of active citizenship that can meet the demands of a world increasingly defined by the processes of globalization. Ultimately, that is what will end up combining a valid notion of active citizenship with effective decision-making procedures in pluralistic democracies. More than a simple summary of research, Challenges to Democratic Participation is designed to be accessible and useful to a wide variety of audiences, from scholars and practitioners working in numerous disciplines and fields, to activists and average citizens who are interested in seeking a theoretical groundwork for democratic practices; it also intends to enhance current scholarship, serving as a guide to existing research and identifying useful future research.