The Order of Saint John of Jerusalem is one of the oldest institutions in the world. Established in the 1040s originally for the care of pilgrims to the Holy City, the Order achieved fame during the crusades, and since that time has operated as a military and religious order, and Hospitaller organisation. This paper examines the features of the Order’s longevity and adaptation over the centuries through to its position in the modern world. The Order is considered by some to be a relic of the crusades, and a secretive elitist club. Yet the considerable funds raised and used on humanitarian projects in all parts of the globe, diplomatic record at the United Nations and vast volunteer networks suggest that the Order is performing as valued role today as it was a nine hundred years ago.