Previous studies have defined the earliest stage of child language to be the stage at which an uninitiated speaker of adult language can understand sentences spoken by the child. Upon the examination of the language of one child, aged 1 year and 7 months, it became evident that she could talk, even though it was equally evident that she didn't use sentences. Her usage was explained on the basis of "vertical constructions" as opposed to "horizontal constructions" or sentences. Four types of vertical constructions were analyzed in this child's speech: Type A, which is the last to develop, consisting of two or three utterances in close succession; type B, which is like type A, except that the words may be repeated; type C, which is also like type A but involves the intervention of another speaker; and type D, which is like C with repetition of some words. Within the structure of the vertical constructions, one discovers two-word horizontal components, suggesting the possibility that vertical construction is at the heart of the structure of discourse. The data on vertical constructions have been ignored by most investigators since successful sentence usage was not involved, but by expanding one's analysis to include one-word utterances, repetitions, and "unintelligible" utterances, it can be seen that the child is learning to speak meaningfully at a much earlier age than was previously thought. (LG)