The present paper explores the notion of multimodality in a developmental perspective both in deaf and hearing children with the aim of showing that the nature of gesture in language is functional to the mode of communication. Research on various sign languages has revealed that mouth actions often accompany sign language utterances, along with other bodily components, and has paralleled them to co-speech gestures. Mouth actions will be described from a developmental perspective and compared to the cospeech gestures of hearing children. Specifically, mouth actions and manual gestures will be investigated in two groups of 10 bilingual italian/italian sign language (lis) deaf and hearing children, aged 6 to 14, using a naming task. The goal is to quantitatively and qualitatively compare mouth actions and co-verbal gestures to understand their roles in sign and vocal naming. Additionally, three adult signers were analyzed as control group to understand the types and occurrences of mouth actions in adult signing for a naming task and to compare these with the signing of children.