The relation between conversation and language development will be considered from two perspectives. The first concerns the acquisition of the conversational skills that are necessary to become a competent speaker of a language, such as mastering the implicit rules of turn taking in conversation, directing the interlocutor's attention, initiating and maintaining conversational topics, interacting in accordance with the implicit communicative rules of cooperative interaction (Grice, 1975:48). This implies behaving according to specific principles that require offering relevant contributions that take into account the knowledge interlocutors have of the verbal and nonverbal context, or of previous discourse, to select appropriate expressions. The second concerns the contribution of conversational functioning to children's acquisition of language knowledge from the early stages of development. The reasons for which conversational functioning can impact language acquisition will be specified and results relevant to the theoretical claims will be reviewed for typically developing and language impaired children. It will be emphasized that unlike general input and from child-directed speech, conversational exchanges are intricate interactional phenomena whose unfolding and effects result from the contributions of all participants and depend heavily on children's own level of competence.