World Politics

What accounts for the waves of policy diffusion that increasingly sweep across regions of the world? Why do many diverse countries adopt similar changes? Focusing on the spread of Chilean-style pension privatization in Latin America, this article assesses the relative merit of four theoretical explanations that scholars of diffusion have proposed. As the principal mechanism driving innovations' spread, these approaches emphasize external pressures, emanating especially from international financial institutions; the quest for symbolic or normative legitimacy; rational learning and cost-benefit calculation; and cognitive heuristics, respectively. The article assesses which one of these frameworks can best account for the three distinctive features of diffusion, namely its wavelike temporal pattern; its geographical clustering; and the spread of similarity amid diversity. While several approaches contribute to understanding policy diffusion, the analysis suggests that the cognitive-psychological framework offers a particularly persuasive account of the spread of pension reform.