Previous research has suggested that adopting a transformative school organisation perspective when implementing ESD may be more productive than the previously recommended transmissive perspectives, but it is not clear how transformative perspectives could be introduced. 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' leaders, who were responsible for implementing ESD, were interviewed to obtain information on the quality criteria they used to guide their work. The arguments used by the leaders to justify their criteria were analysed and categorised based on their relationships with the transmissive and transformative quality strategies. Both school organisation perspectives were found to co-exist within the schools. A detailed analysis of schools where the transformative perspective was dominant revealed three distinct quality strategies, one of which was found to embody a strong focus on a transformative approach. This specific quality strategy is discussed and suggested as a way for interested schools to implement ESD in a more transformative way at the school organisation level. [For Part 1, see EJ1148190.]