The practice of policy advocacy has outpaced its theoretical development. Yet the importance of a theoretical grounding for advocacy has increased as advocacy organizations demand measures of efficacy, and theories of policy development need to account for advocates' contributions to the process. This article begins to address these issues by developing a conceptual framework of policy advocacy inputs, activities, and outcomes. Logic models of practitioners' advocacy programs were first synthesized into a general model. Then academic theories from social sciences and especially policy studies were reviewed and applied to hypothesize links between advocacy inputs and activities, and between activities and outcomes. The result is a conceptual framework of policy advocacy to focus academic attention on this topic, and to direct a research agenda.