Referring a patient to a neuropsychologist for evaluation provides a level of rigorous assessment of brain function that often cannot be obtained in other ways. The neuropsychologist integrates information from the patient's medical history, laboratory tests, and imaging studies; an in-depth interview; collateral information from the family and other sources; and standardized assessment instruments to draw conclusions about diagnosis, prognosis, and response to therapy. Family physicians can use this information in the diagnosis and treatment of patients with depression, dementia, concussion, and similar conditions, as well as to address concerns about decision-making capacity. Certain assessment instruments, such as the Mini-Mental State Examination and Patient Health Questionnaire-9, are readily available and easily performed in a primary care office. Distinguishing among depression, dementia, and other conditions can be challenging, and consultation with a neuropsychologist at this level can be diagnostic and therapeutic. The neuropsychologist typically helps the patient, family, and primary care team by establishing decision-making capacity; determining driving safety; identifying traumatic brain injury deficits; distinguishing dementia from depression and other conditions; and detecting malingering. Neuropsychologists use a structured set of therapeutic activities to improve a patient's ability to think, use judgment, and make decisions (cognitive rehabilitation). Repeat neuropsychological evaluation can be invaluable in monitoring progression and treatment effects.