Assessment of communication by a patient with a speech disorder by clinicians is often dependent on whether the patient makes an appropriate response to an instruction. The speech therapist concerned with language usage and the over-all ability to communicate has developed skills and investigational techniques to identify subgroups within the broad categories of speech pathology appreciated by the clinicians. This prospective study of 100 patients with neurological disease referred for speech therapy, examined in detail in good working conditions and with ample therapy time, is intended to clarify for the clinician a method of assessment, and to illustrate the value of therapy, and establish a prognosis for the variety of speech and language disorders encountered.