How should we think about and understand human behaviour? What's the role of theoretical models? How can - and should - such models be used in practice? And what can we learn from the many different academic and practical perspectives on the subject? This book, aimed at anyone with an interest in behaviour change, offers a fresh and challenging take on these questions. It comprises a Dialogue, which sets out key debates in a lively and accessible way, and 21 commentaries written from a wide range of standpoints, including academic, commercial and public sector.