This book reviews the full coaching outcome research literature to examine the arguments and evidence behind the use of executive coaching. Erik de Haan presents the definitive guide to what works in coaching and what changes coaching brings about, both for individual coaches and for organisations and commissioners. Accessibly written and based on contemporary quantitative research into coaching effectiveness, this book considers whether we know that coaching works, and, if so, whom it works for, and what it offers to those involved. considers the entire body of academic literature on quantitative research in executive and workplace coaching, assessing the significant results and explaining how to apply them. Each chapter contains direct applications to coaching practice and clearly evaluates the evidence, defining what really works in executive coaching. Alongside its companion volume , this book is an essential guide to evidence-based effectiveness in coaching. It will be a key text for all coaching practitioners, including those in training.