The health impact of radiological and nuclear emergencies can last for decades. Lessons learned from past radiological and nuclear accidents have demonstrated that the mental health and psychosocial consequences can outweigh the direct physical health impacts of radiation exposure. International radiation emergency preparedness and response standards outline provisions for mitigating these effects. Yet, practical guidance for addressing the mental health and psychosocial aspects of radiation emergencies remains scarce. A Framework for Mental Health and Psychosocial Support in Radiological and Nuclear Emergencies was developed to fill this gap while building upon existing World Health Organization (WHO) and InterAgency Standing Committee (IASC) guidelines for providing mental health and psychosocial support (MHPSS) in emergency settings. This framework aims to promote integration between the MHPSS and radiation protection fields. It is intended for officials and specialists involved in radiation emergency planning and risk management as well as MHPSS experts working in health emergencies.