Movements of the hands that co-occur with speech - gestures - are the subject of this volume in the New Directions for Child Development series. Although gesture has always been considered relevant to talk, it has usually been seen as a stream separate from speech, one that can reflect the attitudes and feelings of speakers but that is not centrally involved in language. It was not until recently that gesture became a "legitimate" interest of language researchers. The chapters herein focus on the spontaneous gestures that accompany speech, especially the speech of children. Together they confirm that gesture is a robust and integral part of communication that can provide unique insights into the mind.