Within International Baccalaureate (IB) programmes, teachers play a central role in facilitating learning and empowering learners. One of the key competencies required by teachers to be able to support high quality learning is for assessment, teaching and learning in their classrooms to work collectively. Teachers must possess a high level of assessment literacy to properly fulfil their role of supporting teaching and learning. Teachers’ assessment literacy can have an impact on the quality of educational provision. The aim of this study was to develop an assessment literacy and design competency framework for use across IB programmes and professional learning resources.