Dominican Vudu, generally called las veintiuna divisiones, the twenty one divisions, organises its spirits into groups in a manner parallel to Haitian Vodou while differing from it in composition, vocabulary and tone. The spirits are called misterios or luases, and each is identified with a Catholic saint, so that an image on an altar is read by insiders as one being and by everyone else as another.
The principal divisions are usually named as the Rada, associated with water, coolness and benevolence; the Petro, associated with fire, force and speed; and the India division, addressed to spirits understood as Taino, the indigenous people of the island, which is a component with no direct Haitian equivalent and which carries a claim about Dominican origins.
A practitioner through whom a spirit speaks is described as the caballo, the horse, of that misterio. Ceremonies involve drumming, and the palos drums and the fiestas de palos held for a saint's day are the most publicly visible element, often understood by participants and neighbours as Catholic festivity.
The reason the religion is widely practised and rarely acknowledged is political. Dominican nationalism has for a century defined itself against Haiti, and state ideology under Trujillo made African descent and Haitian influence into the things a Dominican was not, a project that culminated in the massacre of thousands of Haitians and Haitian Dominicans in 1937. In that climate, naming a religion as African derived was dangerous, and the habit of not naming it outlasted the regime.
It is a living tradition with initiated practitioners, and much of its content is transmitted only within initiation. The atlas records its structure and leaves the rest alone.