The cognitive functioning of 25 language deficient children, six through eight years of age, was compared with that of 14 matched controls. Language deficiency was defined by verbal IQ below 90 and at least 15 points below Performance IQ on a short form of the WISC. Thus the experimental subjects were chosen because of their inadequacies in solving conceptual level tasks presented to the auditory modality. The test battery used to measure cognitive adequacy consisted of visually and auditorily presented tasks which explored both perceptual and conceptual level functioning. The results indicated that language deficiency is a relatively stable condition over a period of one year; that all auditory modality functioning of the experimental subjects, regardless of integrative level (perceptual or conceptual), is significantly below that of the controls; and that visual modality performance of the two groups does not differ significantly. Sensory modality thus proved to be the central organizing factor in the cognitive functioning of the language deficient children. This was not true of the control subjects, whose functioning appeared to be more integrated. Not unexpectedly, teacher reports indicated that the experimental subjects have reading difficulties. Further study of etiology, consequences, and remediation of language deficiency is needed.