Sustainable development has been the focus of many analyses in economics. Nevertheless, only a few attempts have so far been made to identify the underlying relationship between sustainable energy development and sustainable social development. This article fills this research gap and enables a better understanding of the essence of sustainable development to help draw applicable conclusions. The aim is to assess sustainable energy and social development in EU countries and to examine their shared relationship in this area. To this end, this study uses a taxonomic method and correlation analysis. The analysis period covers the years 2014–2020. The research builds directly on the assumptions of the concept of sustainable development, with particular emphasis on energy and social aspects. The article is composed of two parts. The first, based on a literature review, discusses the essence of sustainable energy development and social sustainability. The second outlines the research methodology, including the underpinnings of synthetic measures and the results of the conducted empirical research.