Attempts to involve citizens more productively in public life have proliferated so rapidly that scholars are struggling to catch up. Around the world, community leaders are experimenting with ways to engage residents in public deliberation, decision making, and problem solving. A number of questions and challenges facing public officials, civic practitioners, community organizers, and other leaders could benefit from closer attention by academic researchers. Moreover, aside from these gaps in collective knowledge, the democratic principles evident in the new wave of public engagement initiatives present another challenge to the academy: how to involve citizens more effectively in the research process itself? The complex, continually shifting landscape of citizenship and democracy presents ample challenges for the researcher. When it comes to measuring the outcomes of engagement efforts, there are democratic complications that defy traditional models of research and evaluation, and mesh well with the principles of engaged scholarship and action research. One is faced, then, with a two-sided question: how might researchers contribute to the development of democracy--and how might democratic principles contribute to that research? In this article, the authors suggest some answers to this question and attempt to summarize the existing research on the impacts of deliberative democracy, as well as the gaps where more research is needed. Then, they use several examples to illustrate how action research can be a particularly effective methodology for democracy scholarship and evaluation.