Emergency physicians provide care for an extraordinary broad range of illnesses and injuries, the majority of which involve some degree of pain. Table 36.1 lists major categories of discharge diagnoses among those presenting to a multicenter emergency department (ED) network with a principal complaint of pain. Emergency physicians also frequently cause pain in the course of performing emergent therapeutic and diagnostic procedures. This chapter considers the prevalence of pain in the emergency department, barriers to its adequate treatment, as well as a variety of treatment modalities. Space limits prohibit a discussion of the wide variety of specific painful conditions that present to the ED. These can be found in other chapters of the text. Prevalence and Assessment of Pain in The Emergency Department Pain is the presenting complaint for up to 78% of visits to U.S. EDs. Although making an accurate diagnosis and choosing the appropriate therapy to treat underlying conditions are principal goals for emergency physicians, those who present to the ED with pain seek recognition of their pain and rapid, effective interventions to control pain. In the United States, the ED serves as a safety net for our fragmented health care system, and pain is but one of many conditions for which emergency physicians not only treat acute clinical presentations but also care for those with chronic or recurrent painful conditions who are unable to access other parts of the health care system.