In their study of media content, mass communication scholars commonly rely on Entman's (1993: 52) definition of framing: "[selecting] some aspects of a perceived reality and make them more salient in a communicating text, in such a way as to promote a particular problem definition, causal interpretation, moral evaluation, and/or treatment recommendation." Much of the study of media framing of political issues centers around three questions: (1) How is the issue framed?; (2) How can we explain variation in framing—both over time and cross-sectionally?; and (3) What are the effects of media framing on public opinion and policymaking? These questions are also of clear relevance to the study of social movements (see also Snow 2008).