Unexplained crying in young babies is a common and puzzling phenomenon. Stimulated by this, the last few years have brought paediatricians and developmental psychologists together, with the result that many traditional assumptions have begun to be questioned or overturned. This book is the first to draw this developmental perspective together, so that it is a welcome addition to the literature.

The book's enigmatic title refers to the distinction between crying behaviour as a “sign” of an underlying disease, a “symptom” (which the editors define as a more subjective report or complaint by a patient), and a “signal” which has communicative purposes. Their introductory chapter proposes that crying can serve all three …