Colwyn Trevarthen’s seminal work has earned him a place alongside the most prestigious thinkers, writers and researchers into human development. He is universally acknowledged as the pre-eminent expert on foetal, neonatal and early childhood development. Sandra Smidt examines the impact of his scientific training, linked to his interest in how filmed episodes of mother or father/baby interactions might inform his understanding about early sociocultural development, encouraging us to view the human infant with fresh eyes and realise how purposive human behaviour is from the start. His interest in and collaborations with others introduce the reader to the idea of communicative musicality which, together with physical movement, lead the child to acquiring language. This book focuses on the earliest years of life and makes complex ideas accessible and applicable to a range of settings. As well as providing a glossary of key terms and an introduction to the life and work of Trevarthen, the book is split into three parts: From foetus to neonate, The remainder of the first year of life and From one to three. Each part offers case studies, practical examples, draws on recent research evidence and includes helpful pointers for students, labelled ‘Think about this’. This essential guide to his work will be of interest to professionals working with children in early childhood settings and to undergraduate students training to become early childhood professionals.