Clinicians and families report that traumatic brain injury results in a variety of attention deficits. Numerous laboratory studies have documented slowing of information processing, alteration in event-related potentials, or difficulty attending to specific relevant task dimensions in the presence of redundant information. However, little is known about how these information processing abnormalities relate to observable behaviors in daily living or work environments, which presumably form the basis for clinicians’ and families’ reports. We developed a quantitative assessment of behavioral inattentiveness in both quiet and distracting environments, and demonstrated excellent interrater reliability. Using this assessment, we have studied 20 patients with recent traumatic brain injury and 20 demographically comparable control subjects. We have confirmed marked differences in behavioral attentivencss between patients and controls in both distracting and nondistracting environments. (JINS, 1996, 2, 274–281.)