The process of public policymaking is normally very complex, involving hundreds of actors from interest groups, governmental institutions, journalists, and the research community who have different goals, perceptions of the situation, and policy preferences. In any given policy domain, such as health care or air pollution control, there are normally dozens of programs involving multiple levels of government. Given this complexity, the analyst must find some way of simplifying the situation in order to have any chance of understanding it. Such simplification involves assumptions about which factors and relationships are critical and those that can safely be ignored.Theories of the Policy Process provides a forum for the proponents of the most promising and widely-used theories to present the basic propositions of their frameworks, to assess the empirical evidence that has developed over the past decade, and to discuss promising directions for future research. The frameworks include the stages heuristic (Jones and deLeon) and comparative state politics framework (Hofferbert and Dye) developed in the early 1970s, as well as several frameworks that have been developed since 1980. These include institutional rational choice (Ostrom, Scholz, Scharpf), punctuated equilibrium (Baumgartner and Jones), multiple streams (Kingdon and Zahariadis), the advocacy coalition framework (Sabatier and Jenkins-Smith), and policy diffusion approaches (Berry and Berry). In addition, Edella Schlager presents a comparative analysis and evaluation of the more recent frameworks, and the editor suggests a number of strategies for improving the state of theorizing in this field.