This paper explores the philosophical orientations within which agenda setting operates, and agenda setting’s place within the broader framework of the media effects tradition, specifically in comparison with framing and priming. It also responds to earlier criticisms of agenda setting for its supposed lack of theoretical richness and narrowly understood underlying mechanisms. Both ontological and epistemological statuses of the agenda-setting theory are analyzed in order to place agenda setting into the communication discipline’s broader context. This paper demonstrates that the most important distinction between framing and agenda setting is that they are based on different ways of knowing. While the epistemological bases of priming are similar to the theory of agenda setting, the paper argues that further progress will depend not only on practical studies of different aspects of agenda setting, but also on theoretical and philosophical conceptualizations in the future.