Four groups of 10 patients, each group having a different neurogenic disorder of communication, were tested for impairment in 10 language categories. Five categories—auditory comprehension, adequacy of response, arithmetic, syntax, and naming—although impaired to some degree in all groups, did not sharply differentiate them. The most strongly differentiating disabilities in the four groups were aphasia—auditory retention span and fluency; apraxia of speech—fluency; confused language—relevance, reading comprehension, and writing of words to dictation; and general intellectual impairment—reading comprehension and auditory retention span (with preservation of relevance). The groups differed also in the onset and duration of the communication difficulty, and in the nature and locus of the neurologic problem.