The aims of our follow up observational study were to c1arify the transition from pre-linguistic communication to early language and to show how dependent the development of verbal behaviour was upon the nature of the interaction taking place between mother and child from the early months. Over a 22-month period fortnightly observations were made of 8 mothers and their firstborn children (2-23 months o1d) as they interacted at home, in natural and in semistructured situations. Maternal and chi1d behaviours were recorded by time-samp1ing method on the observation check1ist consisting of 40 maternal and 65 child categories of behaviour. In the present paper, part of this comprehensive samp1ing was analyzed in terms of (a) frequency of child voca1izations (FIG. 1), gaze (FIG. 2) and facial or gestural communications (FIG. 3), (b) co-occurrence of maternal or child categories of behaviour with chi1d vocalizations, i.e. crying, negative vocalization (TABLE 3), babb1ing (TABLE 4), pre-speech and speech (TABLE 5). It was demonstrated that chi1d speech exhibited after 16 months of age, turntaking (alternation) with his mother ; whereas it was only at the age of 22-23 months that pre-speech being also an intentional voca1ization, exhibited alternation pattern instead of previous coaction pattern. As for babbling, it revealed that it had two functions, i.e. play by oneself and expression of pleasure. The latter exhibited coaction pattern at 2-5 months of age, and the alternation pattern occured after 6 months. On the other hand, crying and negative voca1ization exhibited only coaction pattern (2-19 months).