Among the first baby communications we find the bimodal collaborations of gesture and word. In this chapter we present some considerations on the types of baby gestures and propose a comprehensive observation category system of gestures and vocalizations, either as single signs or in bimodal compositions, based on a relational-semantic pattern. We believe that such a system could bridge the gap between the study of pregrammatical and grammatical communicative expressions. In fact, a multimodal combinatorial role semantics would be better able than other systems to reliably track how simple meanings begin to interweave with one another to express more complex contents within a single message. In this way, the transition from the original multimodal expression to the grammatical form, with its tendency towards unimodality, could be approached in a seamless and integrated manner. In addition, we highlight the pending challenge of expanding the margins of bimodal combinations. In this direction, we point out the need to enrich these categories with the creation of an ecological code of the baby´s integral communication resources, which includes both those signs effectively used in communicative acts and the behavioral variables that accompany these signs and guide the interlocutor with keys for their interpretation.