The objective of this research is to test whether the contents and functions of young children's communication with fathers and mothers differ. Categories based on Speech Act Theory were used for the analysis of functions. As regards contents, messages were classified into three categories: (1) messages which refer to objects, actions or evaluations linked to task performance; (2) messages linked to characteristics of referents which are not linked to task performance; and (3) expressions of internal emotional states. The functions and contents of messages were analysed in two populations: American and French. Children were aged 20 to 26 months and were observed playing with a standard set of toys with each parent separately. The results show that fathers produce more messages linked to task performance and tend to produce more action directives than mothers and that, similarly, children produce more messages linked to task performance and more action directives with fathers than with mothers. Therefore, it seems that as young as 2 years of age, children adjust their communicative behaviours to fit characteristics of the interlocutor. Differences between the populations as well as the more precise nature of mother-child communication are also discussed.