Research on Education for Sustainable Development (ESD) implementation tends to focus primarily on student and teacher outcomes, and there have been few studies on leadership practices at the school organisation level that provide information on how quality in education contributes to ESD implementation. To address this issue, we conducted an empirical mixed methods study of existing practices in 10 highly ESD-active upper secondary schools in Sweden. The schools' principals, who were responsible for implementing ESD, were interviewed to obtain information on the quality criteria they used to guide their work. Twenty-six criteria were identified and grouped into four main principal quality criteria on the basis of statistical analysis: "Collaborative interaction and school development"; "Student centred education"; "Cooperation with local society"; and "Proactive leadership and continuity." This categorization both supports existing research on ESD quality criteria and highlights new criteria that are important but were previously unrecognized. Trends in the identified quality criteria are discussed and related to prior research in order to identify potentially fruitful school leadership and management for implementing ESD at the school organisational level.