In recent years, in the UK, there has been a significant focus on research in Education for Sustainable Development/Global Citizenship Education (ESD/GCE) in initial teacher education and on projects and initiatives used with pupils in schools. However, there has been less specific focus on the "voices" of teachers who have undertaken such projects: the documentation of their perceptions of effective pedagogy for the development of their pupils' learning and, importantly, the development of their own concepts and values in relation to sustainability education as a result of implementing ESD/GCE-related topics. This paper aims to provide data from this relatively under-reported area. It examines what the teachers learned about effective pedagogy from undertaking a systematic study of their own practice in ESD/GCE-based topics, and it highlights the development of their own understanding of, and values about the place of ESD/GCE in the curriculum. The paper presents an analysis of the reflective journals kept by 10 teachers during the planning and implementation of ESD/GCE projects within their own classrooms. Findings emerging from the study were that critical reflection on their work gave the teachers the confidence to adopt the more learner-centred pedagogy of ESD/GCE, and that teachers, too, were able to benefit from the participation in ESD/GCE activities. (Contains 3 tables and 1 note.)