Continuing professional development (CPD) offers a strong opportunity to transform schools quickly enough to support today’s students in developing the capacity to address urgently needed sustainability solutions. While there have been some efforts in these directions, so far attempts have not been made to demonstrate whether these approaches to sustainability CPD can be scaled up internationally to the level necessary to meet the need to integrate sustainability across subjects and grade levels. Through this multi-national collaboration, we shared a model and implemented it across three very different contexts. The results of this two year project are reported and the important contextual factors for the competence development of teachers are identified. The model utilized here demonstrated success despite significant barriers at each implementation site. We identify three universal features that will create transformative sustainability CPDs: 1) Sufficient contact hours 2) Solutions not problems and 3) Competencies not content.