Every nation that has adopted a strategy for the long-term management of its high-level radioactive waste (HLW) and spent nuclear fuel (SF) has opted for disposal in a deep-mined, geological repository. Identifying a site for such a facility has proven to be a technical and social challenge. Over the last 50 years, both challenges have been met (at least so far) in only three out of the ten countries that have tried. This historical experience makes clear how important it is to gain social acceptability for a site's selection: such acceptability is a prerequisite for policymaking in democratic societies. The inability to gain social acceptability has proven to be the Achilles' heel for most efforts to choose a repository site.