Nuclear technology creates complex, international, intergenerational and multi-level risks. While these risks add to the institutional complexity of the global system, they also contribute to the emergence of new forms and practices of risk governance. From the outset, the literature on risk governance explicitly acknowledged the “transboundary, international and ubiquitous” nature of risks (Renn 2008, 43). Yet, in the subsequent decade, the multilaterality of risk governance has received little scholarly attention (see also Kuipers et al, 2018). This special issue of Risk, Hazards and Crisis in Public Policy will focus on the Multilateral Challenges of Nuclear Risks, whereby it addresses safety and security as well as safeguard issues associated with nuclear risks. In this editorial, we will first discuss what we mean by ‘nuclear risk’ and ‘multilateral governance’. We will wrap up by presenting the papers that deal with these multilateral aspects of nuclear risks.