On the back of Research Excellence Framework (REF) 2021, this collection brings together a wide range of authors to consider what has worked well in evaluation of UK research, what could have worked better and where the UK's higher education system should go from here. Chapters in the volume include: (1) The REF: A hydra-headed beast or an effective policy tool? (Nick Hillman); (2) The Research Excellence Framework: 101 (Nick Ellison); (3) The birth, life and legacy of the Research Assessment Exercise (Helen Carasso); (4) Crediting the capital: breaking the taboo around London's research excellence (Diana Beech); (5) Research, innovation and impact in Wales: strength in diversity (Cara Aitchison); (6) Excellent research requires a supportive and inclusive research culture (Clare Viney); (7) The squeezed middle in Scotland (Iain Gillespie); (8) Funding the future (Ellie Russell and Jennie Eldridge); (9) REF 2028? Think again (Peter Mandler); (10) If metrics are the answer, can we agree on the question? (James Wilsdon); and (11) Passing on the baton (David Sweeney).