This publication presents the outcomes of a collaborative study to analyse the status of nuclear decommissioning activities around the world as of 2020. Future evolution of these activities was also considered. The information presented is based on responses to a questionnaire distributed to organizations with responsibility for planning, implementation and oversight of decommissioning programmes, with baseline information on the numbers and current operational status of nuclear facilities being extracted from the online nuclear facilities databases maintained by IAEA. Analysis of the collected data was undertaken at global and regional levels, rather than at the level of individual States or facility sites. The publication is intended primarily to be of use to individuals with policy responsibilities in the area of decommissioning and associated waste management activities, including government officials, regulators, facility manages and service providers.