Impaired attention is commonly observed among schizophrenia patients and those at genetic risk for the disease. This article reviews over 40 studies that used various versions of the Continuous Performance Test (CPT) as the primary measure of attention. These studies of normal subjects, affected patients, and various at-risk populations demonstrate that the CPT is a psychometrically sound procedure that consistently discriminates affected patients from controls. Sufficiently difficult versions of this task have also demonstrated that impaired attention is (1) evident in schizophrenia patients regardless of clinical state, (2) detectable before illness onset, (3) apparently heritable, (4) specific--in terms of distinct profile patterns--to schizophrenia, and (5) predictive of later behavioral disturbances in susceptible individuals. Selected studies are also discussed that examine the role of attentional deficit in the pathophysiology of schizophrenia and its potential consequences for personality development. With respect to pathophysiology, preliminary data suggest that subcortical brain dysfunction has an important role in the attentional deficits tapped by the CPT. With respect to personality, an association between chronically impaired attention and deficient social skills has been found. It is concluded that the CPT is a cost-effective measure of the attentional deficit commonly found in affected schizophrenia subjects and those at risk for the disorder, and is therefore a potentially valuable screening device for preventive intervention programs.