Regime complexes are arrays of institutions with partially overlapping mandates and memberships. As tensions frequently arise among these institutions, there is a growing interest geared to finding strategies to reduce them. Insights from regime theory, science and technology studies, and social network analysis support the claim that "boundary organizations"—a type of organization until now overlooked in International Relations—can reduce tensions within regime complexes by generating credible, legitimate, and salient knowledge, provided that their internal networks balance multiple knowledge dimensions. Building on this argument, this article offers an ex ante assessment of the recently created International Platform on Biodiversity and Ecosystem Services (IPBES). Results from our network analysis of IPBES point to clear improvements compared with similar organizations, although major deficiencies remain. The contribution of this article is threefold. Methodologically, it introduces new conceptual and technical tools to assess the '"social representativeness" of international organizations. Theoretically, it supports the claim that international organizations are penetrated by transnational networks and, consequently, that the proliferation of institutions tends to reproduce structural imbalances. Normatively, it argues that a revision of nomination processes could improve the ability of boundary organizations to generate salient, credible, and legitimate knowledge.