A neuropsychological evaluation protocol was developed and utilized by the five model systems brain injury centers, incorporating tests with demonstrated reliability and validity. Baseline evaluations of 234 patients tested at an average of 49 days postinjury revealed diverse impairments with a majority demonstrating impairments on 9 of 15 measures. Impairments of attention, verbal learning, and motor speed were most noticeable. Repeated measures analysis of results for 49 patients at one year postinjury revealed continuing impairment, but significant improvement was noted for 15 of 22 measures. Gains were most evident on measures of attention, concentration, and verbal learning. © 1993 Aspen Publishers, Inc.