Requests are among the three basic human communicative motives which emerge earliest in ontogeny and the imperative constitutes the prototypical linguistic verb form category for expressing direct requests. In both Modern Greek and Russian, the imperative is differentiated from other verb forms and most verbs distinguish between perfective and imperfective imperative forms. In the present paper, the perfective and imperfective imperative verb forms occurring in the early speech of a Greek and a Russian child and their mothers’ child-directed speech are studied with regard to their frequencies and functions. It will be shown that the perfective/imperfective contrast of imperative forms does not function alike in the two languages. The differences of imperative usage between the two mother-child dyads and the similarities within each of them may be taken as evidence that the children construct the grammatical distinctions of their language on the basis of usage.