This chapter states the problem and describes global governance of nuclear security, including components of the United Nations system, bilateral United States-Russia and other cooperative arrangements, and the nuclear security summits. It assesses the state of nuclear security governance against four global governance disconnects. The International Atomic Energy Agency (IAEA) offers advisory and peer review services on nuclear security to member states on request and has helped them to develop integrated plans for nuclear security improvements and assistance. In January 2012, the Nuclear Threat Initiative (NTI) published a benchmark study, The Nuclear Materials Security Index. Non-nuclear weapons states (NWS) provide confidential reporting on highly enriched uranium (HEU) stocks under IAEA safeguards agreements. Two nuclear security summits have been held, in April 2010 in Washington, DC and in March 2012 in Seoul. A third summit is planned for 2014 in the Netherlands. In the nuclear industry, there exists significant public-private cross-ownership, not just partnership.