Persistent, inconsolable crying in young infants is common, distressing but usually benign. This selective review examines perceptions and perceived origins of this phenomenon in babies where serious pathology has been excluded. Adult brains have evolved to become hypersensitive to infant cries. Babies respond to parental stress by crying more, thus setting up a vicious cycle. Most treatments appear to work largely through a placebo effect. The imperative for healthcare professionals is to reduce parental anxiety by offering reassurance and support.