Objective. How do we explain variations across nations in the incidence of political corruption? Recent theoretical work locates the causes for corruption in a combination of institutional conditions: monopoly power, little accountability, and wide discretion. This focus on the form of political institutions clarifies the micro-scale causes of political corruption, but it leaves unanswered questions about the macro-scale causes of corruption.

Methods. This article addresses these questions about the macro scale through an analysis of perceived levels of corruption across nations.

Results. Our work identifies poverty, large populations, and small public sectors as contextual causes of corruption. Historically-based differences in political cultures across broad geographical regions also affect the perceived incidence of corruption in nations.

Conclusion. Further research should attempt to link micro- and macro-scale causes together in a single, multi-scalar model of corruption.