The most widely adopted solution for the definitive management of high-level radioactive waste involves its emplacement in deep geological repositories whose safety should not depend on the active presence of man. In this context, national programmes are considering whether and how to incorporate the concepts of reversibility of decisions and retrievability of waste, including to what extent retrieval can or should be facilitated at the design stage of a repository, and if so over what timescales. This brochure delivers the key findings and observations of the OECD Nuclear Energy Agency (NEA) project on reversibility and retrievability conducted from 2007 to 2011 with the participation of 15 countries and 2 international organisations. It outlines the activities undertaken and points to further resources. While focused on deep geological disposal, the pragmatic and precise information provided may also be pertinent to sub-surface disposal and to decision-making processes more generally. This brochure, and related project documents, will be of interest to technical and policy professionals and civil society stakeholders concerned with radioactive waste disposal.