Dynamic Assessment (DA) is an interactive form of cognitive assessment used by some educational psychologists (EPs) to assess the learning potential of children and young people, through a focus on cognitive and affective aspects of learning. In terms of UK EP practice, this approach has the potential to complement the focus on 'person-centred planning' set out in the Special Educational Needs and Disability Code of Practice. However, there is little guidance or consensus on what constitutes good DA practice. This research employed a Delphi methodology to identify competencies required to carry out quality DA. A panel of five international experts in DA and 17 EPs, using DA in practice, participated in three rounds of a Delphi study that identified 13 knowledge and 12 skills competencies considered essential for quality DA practice. The resulting framework could inform training and professional development programmes for EPs wishing to develop their skills and competence in practice.