Neuropsychological tests are increasingly being used as outcome measures in clinical trials of brain tumor therapies. This study informs development of brief neurocognitive batteries for clinical trials by identifying cognitive tasks that detect effects on a group level in a mixed brain tumor population. This is a retrospective study of brain tumor patients who completed a standardized battery sampling multiple cognitive domains using twelve subtests with widely-used task formats (the Repeatable Battery for the Assessment of Neuropsychological Status). Sixty-eight patients with brain tumors were studied (60% high-grade glioma). Forty patients (58.8%) were impaired (>2 standard deviations below published means) on at least one subtest. A combination of four subtests (Figure Copy, Coding, List Recognition, and Story Recall) captured 90% of the impaired subgroup. These results suggest visuoconstruction, processing speed, and verbal memory measures may be the most important domains to assess when evaluating cognitive change in brain tumor clinical trials.