How do different professional structures shape the economic ideas that international economic organizations use to prescribe policy recommendations or derive legitimacy and authority for them? The comparative professional field analysis proposed herein deploys a novel combination of content, network and regression analysis to uncover the precise role of different qualifications, experiences and hierarchies in shaping the economic expertise invoked by the European Central Bank's and the International Monetary Fund's main policy documents, with a specific focus on debates over fiscal consolidation in the wake of the global financial crisis of 2008. The findings challenge much of the scholarship about how economic ideas diffuse across professional domains and where change on macroeconomic policy in international economic organizations is likely to come from. As such, the article should be of interest to scholarship on international bureaucracies, the politics of professional knowledge and the international political economy of fiscal consolidation.