As evidenced by the vast array of literature on the subject of international environmental regimes, the environmental field has provided a wealth of material for international relations theories on the creation, implementation and, ultimately, effectiveness of international organizations (IOs) (cf. Zürn 1998; Mitchell 2002). IOs are typically a distinct component of international environmental regimes and quite often play an active role in creating and implementing those regimes. Yet, their role in these processes has received little specific attention to date (Biermann and Bauer 2004, 2005). Several chapters in this volume address the role of IOs in policy implementation in various policy fields by looking at the material resources they have at their disposal. Here, I will focus on the authority IOs enjoy as bureaucracies and assess how this authority has affected the implementation of international environmental agreements.