ABSTRACT
Studies of American political development emphasize the importance of evaluating the evolution of the political order over the long term. The historical institutionalist approach specifi cally emphasizes the ways in which a particular course of action can become locked in over time. Political institutions, established in one period, may have important effects on the subsequent period, in ways that were not intended or anticipated at the time. Whether political institutions are the result of “framers’ intent” or whether political institutions can best be seen as the codifi cation of the results of particular power struggles, once in place, the structure of institutions sets limits on policy change and shapes the process of contestation. Policy changes in one historical period constitute policy legacies that foreclose other policy options at later points or that render alternative courses of action expensive or diffi cult. The political opportunity structure for social movements is also altered by these changes, in particular, creating obstacles and openings for social movements to infl uence policy and encouraging particular forms of social movement organization and mobilization while discouraging others.
