When Viviane Robinson was asked by the New Zealand government to conduct a review of school leadership research into what school leaders did that made the biggest difference to pupil outcomes, her team identified five key factors. The most important of these, at least twice as impactful as any of the other factors, was effectively about supporting teachers to become better teachers. Yet this research also suggested that school leaders spend as little as 16% of their time on this important work. In this timely book, Zoe and Mark Enser not only make a compelling case for why CPD matters and what great CPD looks like, they crucially identify the difference between learning and development. Only the latter will make a long-term and sustained impact on teacher professional practice and pupil outcomes. Superbly evidenced and elegantly structured, this book is a manifesto for what great CPD can be and yet so often isn't. Backed up by powerful case studies from an impressive array of contributors, it brings alive what the very best of our schools are already doing. As they candidly acknowledge themselves, reading this book won't make any difference in itself, but if every head and senior leader had access to the excellent thinking and analysis in this text, we would at least have a fighting chance of making CPD something teachers and support staff up and down the land will both look forward to and value. Our profession deserves nothing less.