Between 10 and 24 months of age typically developing children progress from communicating through conventional signals to using symbols, both gestural and vocal. The present study investigates this transition tracing the developmental curves in mother-child communication frames and in the child's communicative acts through hierarchical linear modelling. Eight children (4 girls, 4 boys) and their mothers were intensively observed over the second year, using a multiple case-study method. Mother-child dyads were videotaped bi-weekly in a laboratory playroom. As far as mother-child frames, we confirmed in a larger sample the developmental sequence previously reported, i.e. that conventional frames bridge the transition from attentional to symbolic frames. As far as the child's communicative acts, we identified the developmental trajectories for the ability to produce gestural acts (pointing, deictic gestures and representational gestures), verbal acts (words and multi-word utterances) and for the ability to combine words and gestures (crossmodal combinations). The growth curves reported partly confirm previous results mainly based on cross-sectional studies and partly provide new findings.