This chapter provides an overview of the historical context, funding environment, and accountability architecture for transnational non-governmental organizations (TNGO) in the United States (US), and describes specific attributes of US TNGOs and of the sector overall. The United States has played a significant role in the development, growth, and nurturing of the global TNGO sector, both through its domestic policies and through its international engagement abroad. Public policy in the US has actively sought to encourage a vibrant charitable sector, which has proven to be very conducive to the flourishing of TNGOs in the US. Government policy has been a major catalyst in the development of the US TNGO sector. US-based TNGOs became important providers of humanitarian aid in the wake of ethnic conflicts in the Balkans, Rwanda, and elsewhere, and became providers of ‘technical assistance’ to help formerly socialist states adapt to global capitalism and integrate into the newly transformed international system.