This article provides a representative bureaucracy perspective on staff composition in international organizations. Contrary to previous studies in international relations, I argue that staff composition is not only driven by power but international organizations are also concerned with bureaucratic representation. Therefore, I examine one potential barrier and one driver to passive representation namely the available local labor pool and political representation. The empirical analysis is based on an original database of human resources statistics in the United Nations Secretariat which allows for a differentiation between staff categories. The resulting regression analyses suggest that headquarters locations, political representation, and diplomacy are the main determinants of member states’ representation, but these determinants vary in strength depending on the staff categories. This article contributes to the study of staff composition in IOs by examining additional determinants and to the recent discussions on representative bureaucracy at the international level.