This document is a summary of the report "What Makes Great Teaching". It argues that improved teacher ­development will positively impact on pupil attainment, particular those from disadvantaged backgrounds. "Developing Teachers" presents five policy recommendations which have been signed by 17 of Britain's leading headteachers (who, in November, 2014 attended a Washington DC summit on professional development with colleagues from ten countries jointly organised by the Sutton Trust and the Bill & Melinda Gates Foundation). Recommendations include the following: (1) Establishing a strong entitlement for all teachers and school leaders to professional development backed by a College of Teaching and a revitalised National College for School Leadership; (2) Placing greater trust in teachers and increasing their autonomy; (3) Use of evidence to improve standards; (4) Encouraging and incentivising collaboration between schools; and (5) A more developmental approach to accountability including an inspection system that encourages innovation rather than focusing on narrow grades and rankings. The report also presents practical case studies of professional development in schools around the world, and a discussion of how to make time for professional development and reflections on the challenges for school leaders in struggling schools. Links to key resources are provided. "Rubric for assessing trust and transformational leadership practice" can be viewed in the Annex.