The budget process is increasingly considered key for reform efforts to improve fiscal outcomes. In this paper we embark on a political economy analysis of the budget process in Argentina, in the spirit of the IDB project “Political Institutions, Policymaking Processes and Policy Outcomes” in order to understand who determines budget outcomes in Argentina. In particular, we seek to characterize the institutional framework that regulates the budget preparation, approval, implementation and control. Furthermore, we identify which actors are involved both formally and informally in the process at each stage, and seek to understand their incentives and interactions.