Over the past thirty years, the atom has been put to a multitude of peaceful uses. At the same time, the spread of nuclear weapons has been limited, and the bomb has not been used again. We have created an international regime that has allowed atomic energy to be used safely around the world. Institutions such as the IAEA have been established. Rules have been codified in important instruments like the NPT, the Treaty of Tlatelolco, and the NSG. Norms of behavior have evolved through a myriad of bilateral and multilateral contacts.