This research is a synthesis of studies carried out in 18 countries to identify contributions of education for sustainable development (ESD) to quality education. Five common questions were used for the interviews in each country to solicit education leaders and practitioners' views on the outcome and implementation of ESD. The analysis revealed that major themes repeated across the 18 studies, showing that ESD contributes in many ways to quality education in primary and secondary schools. Teaching and learning transforms in all contexts when the curriculum includes sustainability content, and ESD pedagogies promote the learning of skills, perspectives and values necessary to foster sustainable societies. The research also identified the need to integrate ESD across all subjects, to provide professional development for teachers to ensure ESD policy implementation and to adopt ESD management practices to support ESD in the curriculum in order to broaden ESD across countries.