What is a mystic society? Mobile’s Mardi Gras organizations are called mystic societies; New Orleans’ organizations are usually called krewes. They are private, nonprofit groups that celebrate Carnival, either with a parade, or a ball, or both. They meet year-round to plan out each year’s theme and events. Some groups, known as “non-parading societies,” hold a ball, but do not put on a public procession. The largest parading groups build and store their own floats; some of the smaller groups rent floats from the larger groups for their parades. Most of the mystic societies keep their members’ identities secret, a tradition from the earliest Medieval Carnival celebrations when revelers wore masks to add a layer of intrigue and excitement.