The structure of international, national, and non-governmental agencies that participate in the worldwide activity to control nuclear proliferation is discussed here. The International Atomic Energy Agency (IAEA) is described from the standpoints of its organization, reporting functions, the treaties behind its functions, and the technical support that it provides. Its role in safeguards and verification, upholding the standards of the Additional Protocol, and promoting peaceful uses of nuclear energy are detailed. Next, the organizations within the US government involved in nuclear proliferation are discussed: these include the Departments of Homeland Security, Energy, State, and Justice. The US Intelligence Community, with its seventeen individual branches is discussed. The nonproliferation-relevant activities in the US Nuclear Regulatory Commission are also outlined. Next the role of non-governmental organizations (NGOs) is discussed. Their activities include promoting international peace and security, publicizing nuclear construction and service activities, and providing guidance and advocacy on export control issues related to nuclear proliferation.