Imitation in the speech of the child serves at least three functions in the development of linguistic competence. Imitation provides auditory feedback for phonological and morpho-syntactic accuracy, produces a model for verification and/or clarification by speakers, and "makes time" for the processing and acquisition of information. Beyond these functions, however, imitation of the sibling model is different from imitation of the adult model. The second child is provided with a model of speech act behavior appropriate not only for the situation at hand, but for the child participant. Children imitate linguistic forms they do not possess, apparently with the confidence that they want the same result as they see their models obtain. For second children, imitation is oriented more toward achievement of the same goal, and overall, it results in less direct linguistic experience for them. They acquire features of language behavior before mastering those of linguistic form, thereby appearing to reach a stage of language competence earlier than does the first-born. (Author/CFM)