The mental status examination includes general observations made during the clinical encounter, as well as specific testing based on the needs of the patient and physician. Multiple cognitive functions may be tested, including attention, executive functioning, gnosia, language, memory, orientation, praxis, prosody, thought content, thought processes, and visuospatial proficiency. Proprietary and open-source clinical examination tools are available, such as the Mini-Mental State Examination and the Mini-Cog. Physician judgment is necessary in selecting the most appropriate tool for an individual patient. These tools have varying sensitivity and specificity for neurologic and psychiatric disorders, but none are diagnostic for any mental status disorder. Each must be interpreted in the context of physician observation. The mental status examination is useful in helping differentiate between a variety of systemic conditions, as well as neurologic and psychiatric disorders ranging from delirium and dementia to bipolar disorder and schizophrenia. There are no guidelines to direct further testing in the setting of an abnormal mental status examination; therefore, testing is based on clinical judgment.