We have had invaluable help in writing this book. We are extremely grateful to Maria Cotofan, Micah Kaats and Ekaterina Oparina for their skillful research support, and to Jo Cantlay for her brilliant management of the manuscript from beginning to end.

The first draft of this book was subjected to a two-day chapter-by-chapter review in July 2021 in the beautiful setting of Magdalen College, Oxford. The reviewers were: Christopher Barrington-Leigh, Meike Bartels, Timothy Besley, Andrew Clark, Paul Dolan, Sarah Fleche, Philip Good, Carol Graham, Claire Haworth, John Helliwell, Christian Krekel, Stephen Machin, Alan Manning, George MacKerron, Andrew Oswald, Michael Plant and Laurie Santos.

Many others have also given us valuable help and advice, including Lucy Bailey, Lucy Bowes, David Clark, Thalia Eley, Peter Fonagy, David Halpern, Daniel Kahneman, Grace Lordan, Alistair McGuire, Geoff Mulgan, Stephen Nickell, Steve Pischke, Robert Plomin, Robert Putnam, Andrew Steptoe, Graham Thornicroft and Lovis Wentworth.

We would like to thank the many generous donors who have supported our recent research programmes at the LSE Centre for Economic Performance and the Wellbeing Research Centre at the University of Oxford and, through that, this book. They include the ESRC, the What Works Centre for Wellbeing, the Illy Foundation, Rishi Khosla, Pavel Teplukhin, Sushil Wadhwani, Andrew Barnes, KSI Education, Wellbeing for Planet Earth Foundation, Victor Pinchuk Foundation, and the Robert Wood Johnson Foundation.

Finally, we are hugely indebted to our colleagues at the Cambridge University Press (CUP), especially our editor Philip Good, and to our agent Caroline Dawnay who arranged our marriage to CUP.

Thank you all.

Richard and Jan