Previous work has suggested that normal subjects are able to recognize and correct their own errors of movement without using exteroceptive signals. This ability may be impaired in schizophrenia. Twelve normal subjects, 12 alcoholics, and 14 schizophrenics performed a step-function tracking task designed to prevent the use of exteroceptive signals in correcting errors of movement. The mean probability of correcting an error without external cues was approximately .38 in schizophrenics, .70 in normal subjects, and .75 in hospitalized alcoholic patients. There was no difference between groups in the ability to initiate correct responses. The results suggest that schizophrenics are deficient in the ability to monitor ongoing motor behavior on the basis of internal, self-generated cues.