This book explores the influence of private United States (US) philanthropic foundations in the governance of global problems. Through a close scrutiny of four high profile case studies of public-private collaboration, the work addresses the vacuum present in global governance scholarship regarding the influence of foundations, arguing the influence of these actors extends beyond the basic material, and into the more subtle and complex ideational sphere of policy and governance. This book: Charts the growth of private forms of governance and foundations' role in deepening and extending private power in global politics Provides a historical examination of private foundations in international affairs including their centrality in the development of the institutional architecture in international health and agriculture and the linkage back to domestic political systems Analyses the new modes of philanthropy and giving styles particularly venture philanthropy and 'philanthrocapitalism' and how these are being rearticulated in the aid architecture and in development discourses Evaluates distinctive features and unique attributes of foundations as transnational actors(including their limitations) how they use these attributes when exercising policy influence and how they negotiate and collaborate with other state and non-state actors in global governance Provides an introduction to three prominent foundations Gates, Rockefeller and the Acumen Fund and four key partnerships IAVI, GAVI, AGRA and A to Z textile Mills. This work will be of great interest to students and scholars of international organizations, international political economy and development studies.