Speech is normally accompanied by numerous body movements such as hand gestures, head nods, posture changes, etc. These are known to have communicative and regulatory functions such as clarifying or emphasising messages, regulating speaking turns, etc. In addition and in parallel to these, it is argued, body movements have specific speech productive functions, primarily the facilitation of lexical selection and the regulation of prosodic features. Movements serving the two functions differ in many ways, e.g. in their kinematic properties, complexity, timing in relation to speech, impairment in aphasia, mode of encoding and the stages of speech processing in which they originate. These differences are emergent, rather than prescriptive or rule-governed, originating in cognitive and motor constraints. The functional utilisation of body movement is locally optional.