The present document provides a summary of the progress made by the Economic Commission for Europe (ECE) and the United Nations Member States in implementing the ECE Strategy for Education for Sustainable Development (ESD) during the implementation phase 2017–2019 (also referred to as the “implementation phase IV”). The present synthesis report is based on the analysis of 34 national implementation reports submitted by Member States for that phase. The national implementation reports, reveal that many countries have policies in place to support ESD but the challenge remains of coordinating those policies and increasing the number of countries with national implementation plans for ESD, as observed during the previous implementation phases. Many countries have expanded policies to the non-formal and informal sectors, encouraged synergies and involved various stakeholders in ESD. However, the ‘whole-institution approach’ needs to be re-examined and further implemented in the context of some countries, mainly in relation to incentives and policies. In almost all countries, educators reported having received training on ESD competences during pre- and in-service training. Tools and materials for ESD are widely produced through national strategies and investment of public money, but more needs to be done in terms of dissemination and accessibility of materials and the establishment of quality control criteria. Many Governments recognize the need to connect research to ESD policy and practice. Concerning the promotion of research and development, the weakest element is the evaluation of the Strategy’s outcomes.