This article explores the relationship between two prominent varieties of democracy and the size of a country’s prison population. Theoretically, it proposes that social democracies increase social and economic equality which reduces both the “demand for crime” and the number of criminals. Adversarial democracies, on the other hand, generate higher levels of inequality and insecurity that lead to higher levels of crime. Utilizing a structured, focused comparison of Nordic social democracies and Anglo-American adversarial democracies complemented by cross-sectional multiple regression analysis of twenty industrialized democracies, I find empirical support for both of these conjectures. A major implication of this study is that states which choose parliamentary democracy,proportional representation elections, and a social democratic orientation may have a long-lasting positive impact on crime reduction by helping to remedy underlying structural causes of political, economic, and social inequality that give rise to criminal behavior.