His primary research interests are in comparative politics, and focus on the consequences of economic inequality for political attitudes and behavior. His work on this topic has appeared in the American Journal of Political Science, the British Journal of Political Science, and Political Behavior. To facilitate this research, he created and maintains the Standardized World Income Inequality Database (SWIID), which provides the most comparable data available on income inequality for countries around the world over the past half-century. While at Princeton, he will be writing a book examining the relationship between economic inequality and nationalism.