Despite extensive commentary on the failure of health care reform, little systematic analysis has addressed the question of why reform became a national political issue in the early 1990s. Drawing on studies of agenda setting and examining opinion surveys, media coverage, and various measures of congressional activity, I identify the major factors that pushed health care reform onto the government agenda and explore the relationships among them. These factors fall into three categories: the underlying structural changes in Congress and the interest group community that created a receptive climate for addressing health care reform; more immediate changes in the medical system, public opinion, media coverage, and the budgetary and political environments that increased attention to the issue; and a crucial political catalyst that thrust the issue to the top of the government agenda—-the 1991 victory of Harris Wofford in a special Senate race in Pennsylvania. A content analysis of media coverage of that election reveals that journalists and politicians rapidly interpreted Wofford’s triumph as a sign of broad-based public support for reform. This widely shared interpretation redefined the political risks and benefits of health care reform, creating an opportunity for legislative action. Partly because of the way reform reached the government agenda, however, this window of opportunity was more fragile than many believed. My argument thus has implications not only for agenda-setting research but also for the failure of national health legislation and the future possibilities for reform.