The Most Venerable Order of the Hospital of Saint John of Jerusalem (French: L'Ordre très vénérable de l'hôpital de Saint-Jean de Jérusalem), is a royal order of chivalry established in 1831 and found today throughout the Commonwealth of Nations, Hong Kong, Ireland and the United States of America. Its world-wide mission is "to prevent and relieve sickness and injury, and to act to enhance the health and well-being of people anywhere in the world." It is often simply called the Order of St. John, or as the Venerable Order of Saint John (VOSJ) to distinguish it from other similarly named orders.
The order's approximately 25,000 confrères, supported by 4,000 employees and 250,000 volunteers, are mainly Anglicans, though those of other Christian denominations or other religions are accepted into the order, and honorary membership is presented to distinguished adherents of other religions. Membership in the order is by invitation only, except via appointment to certain government or ecclesiastical offices in some realms. People may not petition for admission. It is perhaps best known through its service organizations, St. John Ambulance and St John Eye Hospital Group, the memberships and work of which are not limited to any denomination or religion.