This investigation addresses problems of defining verbal imitation, and suggests solutions by analyzing verbal interactions between two children and their mothers. Children were between 18 and 35 months old, with a mean length of utterance between 1.4 and 4.2 morphemes. Analyses focus upon the uses these children made of maternal models; 10 subsets of imitational phenomena are differentiated. Frequencies of these subsets are presented together with the sequential contingencies between maternal antecedents and the subsets of filial imitations. With the younger child, phenomena resembling generalized imitation training were encountered (i.e., the training of a rehearsal strategy and not only the training of specific linguistic contents). With the older child, the variety of interactional patterns and of linguistic contents trained was larger. Microanalyses, based upon verbatim examples of verbal interactions, suggest differential filial processing, either in the sensory register only, in short-term memory, or in long-term memory. These differential levels of processing were sometimes encountered even within the same utterance. A three-dimensional coordinate system is suggested for the differentiation of the various imitative uses of model utterances. The coordinates represent (1) the level of processing of the model, (2) the degree of isomorphy between model and imitation, and (3) the type of learning achieved through these processing strategies. (Author/RH)