Psychiatric emergencies are encountered throughout the practice of medicine, in many clinical settings. They may range from a patient expressing suicidal thoughts in an outpatient medical visit to an agitated, threatening patient with psychosis who is acutely intoxicated brought to the Emergency Department by ambulance. Decisions regarding admission, discharge, treatment, and referral are time-sensitive in the emergency setting or when acute safety issues are at stake. A broad knowledge of psychiatry and an understanding of potential medical etiologies of behavioral changes are important, as well as skills navigating what can be a complicated consultation relationship with the emergency department and challenging systems-based issues. In a time when emergency department visits continue to grow, resources for inpatient beds remain scarce and outpatient care can be difficult to access, the demand for psychiatric care and evaluation in the emergency setting is crucial. This volume, the 12th in the Primer On series, provides a straightforward approach to evaluating and managing common psychiatric emergencies. Blending case examples with up-to-date evidence-based approaches, this book serves as both a reference and introductory text for clinicians who are working in an emergency department or emergency consult setting.