Drawing on "active audience studies" and recent theories of mediation, the concept of "lay theories of media" is proposed as a means to understand how social movement actors think about and interact with news media as part of the "practice" of activism. The argument is made via a case study of the Dissent! network using data gathered from participant observation in the planning and enactment of protests at the 2005 Gleneagles G8 Summit in Scotland and 30 semi-structured interviews with activists. This article argues that Dissent! activists approached Gleneagles with existing knowledge and experience about news media and demonstrates how these "lay theories" informed their activism. The conclusion stresses the utility of "lay theories" in analyzing how perceived knowledge about how the media function influences or underwrites political activism.