The current study scrutinises issues concerning school leaders' education and training on education for sustainable development (ESD). Particularly, it explores principals' self-reported competence for organising and implementing ESD in schools and their needs in education and training in order to effectively lead sustainable schools. Data were obtained from a nationwide survey in 150 primary schools in Cyprus during 2005-2007. The analysis revealed that school principals in Cyprus are poorly equipped for their new role as leaders of sustainable schools and agents of change, and focused on exploring suitable forms, content and approaches for their professional development on ESD. The outcomes are discussed in a national and international context since they have implications for ESD professional development programmes. Finally we discuss the need for upgrading principals' professional development programmes and ideas for further research in the field.