Traditionally, pneumonia is categorized by epidemiologic factors into community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP). Microbiologic studies have shown that the organisms which cause infections in HAP and VAP differ from CAP in epidemiology and resistance patterns. Patients with HAP or VAP are at higher risk for harboring resistant organisms. Other historical features that potentially place patients at a higher risk for being infected with resistant pathogens and organisms not commonly associated with CAP include history of recent admission to a health care facility, residence in a long-term care or nursing home facility, attendance at a dialysis clinic, history of recent intravenous antibiotic therapy, chemotherapy, and wound care. Because these "risk factors" have health care exposure as a common feature, patients presenting with pneumonia having these historical features have been more recently categorized as having health care-associated pneumonia (HCAP). This publication was prepared by the HCAP Working Group, which is comprised of nationally recognized experts in emergency medicine, infectious diseases, and pulmonary and critical care medicine. The aim of this article is to create awareness of the entity known as HCAP and to provide knowledge of its identification and initial management in the emergency department.