Attention is a complex process whose disturbance is considered a core deficit in a number of disorders [e.g., Attention Deficit Hyperactivity Disorder (ADHD), schizophrenia]. In 1956, Rosvold and colleagues [J. Consult. Psychol. 20 (1956) 343.] demonstrated that the continuous performance test (CPT) as a measure of sustained attention was highly sensitive to brain damage or dysfunction. These findings have been replicated with various populations and with various versions of the CPT. The CPT is now cited as the most frequently used measure of attention in both practice and research. Across studies, results are consistent with models of sustained attention that involve the interaction of cortical (frontal, temporal, parietal), subcortical (limbic, basal ganglia), and functional systems including the pathways between the basal ganglia, thalamus, and frontal lobes. Right hemisphere involvement (asymmetric response) is also evident across multiple studies. As such, the CPT demonstrates sensitivity to dysfunction of the attentional system whether this is due to diffuse or more focal damage/dysfunction or in conjunction with any specific disorder. CPT performance can be viewed as symptom specific (attentional disturbance), but it is not disorder specific (e.g., ADHD). Implications for neuropsychological interpretation of CPT results are presented.