This paper examines the perceptual processes that underlie normal language acquisition with relation to perceptual dysfunctions in the aphasic child. Experiments are cited which seem to indicate that auditory dyfunctions may underlie language impairment. Experimental studies of the linguistic systems of the aphasic child seem to support the theory that the deficiency is quantitative (or one of delay in learning) rather than qualitative (or one of manner of learning), and that this deficiency is one of a semantic, rather than syntactic or morphological, nature. (AM)