Published online by Cambridge University Press: 15 January 2018
The adoption of proportional representation in Western Europe has been portrayed as either a defensive or an offensive competition strategy used by established parties to deal with the rise of new parties under majoritarian electoral rules. Neither explanation accounts for PR reform in other regions of the world, where the change took place in the absence of increased party competition. Analyzing the history of electoral reform in Latin America, this article argues that in a context of limited party competition, the initial adoption of PR was part of a strategy of controlled political liberalization promoted by authoritarian rulers. Subdividing this general reasoning, the article shows that PR reform followed different paths depending on the nature of the authoritarian regime and the events that called into question the existing majoritarian electoral system. This argument is supported with a comparative historical analysis of cases within and across each route to reform.