Under what conditions do governments honor their international commitments? This question occupied Thucydides more than 2000 years ago, and it remains a central concern among scholars and policymakers today. My dissertation addresses it by studying the politics of sovereign debt. Controlling for traditional economic factors, the dissertation argues that domestic political institutions interact with concerns about reputation to determine which governments pay their bills to foreigners. The dissertation employs quantitative methods to test a series of institutional and reputational hypotheses against the record of debtor-creditor relations worldwide over the past 100 years. By supporting follow-up case studies in Argentina and Mexico, an International Dissertation Field Research Fellowship would provide the resources necessary to supplement my quantitative analysis with qualitative research.