This paper examines children's overlapping gesture and speech uses. On the basis of caregiver response to child gestures it investigates the semantic relatedness of information being conveyed. In view of prior claims that gestures are often redundant with words, the study examines an Information theory account of redundancy and an Interactive account and shows that when children communicate through a single modality adults provide fewer responses than when children combine modalities, and these responses differ qualitatively from those found in response to multiple modalities. The paper suggests that this provides a motivation for development from using a single modality to using multiple modalities and that neither communicative channel can be considered redundant.