The chapter explores fascinating and intricate collective instruments engaging both private and public actors that have developed over the past seven decades to insure the complex risks associated with the commercial production of nuclear energy. It tells the story of the evolution of the Paris and Vienna Conventions on third-party liability for nuclear accidents. The multifaceted risks involved are reasonably clear, but they are long term in nature. The time horizon for any viable insurance scheme is also therefore extended. While in principle one might imagine that only governments are able to cover liabilities potentially arising from accidents related to nuclear energy production, it turns out that negotiated intergovernmental arrangements enable private insurance providers to play central and expanding roles in much of the world. The incomplete international regime in place today exemplifies a legalized version of collaborative public authority.