Conation, which involves the ability to apply oneself diligently and productively to the completion of a task over time, was compared in groups with and without evidence of brain damage. Both groups were administered tests that ranged from tasks that were presented by an examiner one item at a time (minimal conation), to a task that required the subject to work independently for 30 minutes, with instructions to work as quickly and as accurately as possible. In this study it was not possible to control test content perfectly, but all tasks were primarily verbal in nature. The subjects with brain damage, compared to the controls, showed progressive impairment in accordance with the degree to which the tasks were judged to require conative ability. Conation, which has been a neglected dimension of behavior in neuropsychological assessment, may be the missing link between cognitive ability and prediction of performance capabilities in everyday life. Additional research is needed to investigate further this apparently significant aspect of neuropsychological functioning.