Local policy adoptions provide an excellent opportunity to test among potential mechanisms of policy diffusion. By examining three types of antismoking policy choices by the 675 largest U.S. cities between 1975 and 2000, we uncover robust patterns of policy diffusion, yielding three key findings. First, we distinguish among and find evidence for four mechanisms of policy diffusion: learning from earlier adopters, economic competition among proximate cities, imitation of larger cities, and coercion by state governments. Second, we find a temporal component to these effects, with imitation being a more short-lived diffusion process than the others. Third, we show that these mechanisms are conditional, with larger cities being better able to learn from others, less fearful of economic spillovers, and less likely to rely on imitation.

This article illustrates the use of the directed dyad-year event history analysis to study policy diffusion, with an application to policy changes in the Children's Health Insurance Program from 1998 to 2001. This analysis reveals strong evidence that states with successful policies are more likely to be emulated than are those with failing policies. Evidence of success is especially relevant for policy changes that lower program costs rather than those raising costs, and for changes made by legislatures rather than by administrative agencies. Moreover, this study reveals policy diffusion based on political, demographic, and budgetary similarities across states, rather than simply geographic proximity.

Studies of policy diffusion often focus on the horizontal spread of enactments from one state to another, paying little or no attention to the effects of local laws on state-level adoptions. For example, scholars have not tested whether local policy adoptions make state action more likely (through a snowball effect) or less likely (through a pressure valve effect). This study conducts the first comprehensive analysis of vertical policy diffusion from city governments to state governments, while simultaneously examining the influence of state-to-state and national-to-state diffusion. Focusing on three different types of antismoking laws, we find evidence that policies do bubble up from city governments to state governments. State politics are crucial to this relationship, however, as local-to-state diffusion is contingent on the level of legislative professionalism and the strength of health advocates in the state.

Over the past fifty years, top political science journals have published hundreds of articles about policy diffusion. This article reports on network analyses of how the ideas and approaches in these articles have spread both within and across the subfields of American politics, comparative politics and international relations. Then, based on a survey of the literature, the who, what, when, where, how and why of policy diffusion are addressed in order to identify and assess some of the main contributions and omissions in current scholarship. It is argued that studies of diffusion would benefit from paying more attention to developments in other subfields and from taking a more systematic approach to tackling the questions of when and how policy diffusion takes place.

The scholarship on policy diffusion in political science and public administration is extensive. This article provides an introduction to that literature for scholars, students, and practitioners. It offers seven lessons derived from that literature, built from numerous empirical studies and applied to contemporary policy debates. Based on these seven lessons, the authors offer guidance to policy makers and present opportunities for future research to students and scholars of policy diffusion.

W e present a model of learning and policy choice across governments. Governments choose policies with known ideological positions but initially unknown valence benefits, possibly learning about those benefits between the model's two periods. There are two variants of the model; in one, governments only learn from their own experiences, whereas in the other they learn from one another's experiments. Based on similarities between these two versions, we illustrate that much accepted scholarly evidence of policy diffusion could simply have arisen through independent actions by governments that only learn from their own experiences. However, differences between the game-theoretic and decision-theoretic models point the way to future empirical tests that discern learning-based policy diffusion from independent policy adoptions.

Previous scholarship has demonstrated that female lawmakers differ from their male counterparts by engaging more fully in consensus-building activities. We argue that this behavioral difference does not serve women equally well in all institutional settings. Contentious and partisan activities of male lawmakers may help them outperform women when in a polarized majority party. However, in the minority party, while men may choose to obstruct and delay, women continue to strive to build coalitions and bring about new policies. We find strong evidence that minority party women in the U.S. House of Representatives are better able to keep their sponsored bills alive through later stages of the legislative process than are minority party men, across the 93 rd -110 th Congresses (1973Congresses ( -2008. The opposite is true for majority party women, however, who counterbalance this lack of later success by introducing more legislation. Moreover, while the legislative style of minority party women has served them well consistently across the past four decades, majority party women have become less effective as Congress has become more polarized.

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