What is the Dominican Order? What are Dominicans?

The Dominican Order is a religious community in the Roman Catholic Church. Its founder, Dominic de Guzman (1170-1221), started the order with a mandate to preach the gospel, combat heresy, and promote sound theology. The Dominicans are known primarily for preaching. Understanding the Dominicans’ history, key beliefs, and influential figures helps explain their importance in the medieval and modern church.

In the twelfth and thirteenth centuries, Europe became more urban and educated. At the same time, new ideas entered European society. The Crusades brought increased contact with Islam and reintroduced the works of Aristotle to Western scholars. Dominic recognized that both ordinary people and university students needed clear teaching about Christianity. He believed a new kind of religious order could meet this need through education and preaching.

Dominic received support for his work at the Fourth Lateran Council in 1215. The order was officially approved in 1216 by Pope Honorius III. The Dominicans were one of several mendicant orders founded during this time, alongside the Franciscan, Augustinian, and Carmelite Orders. These groups took vows of poverty, lived among the people in cities, and were known as friars. The Dominican movement also included nuns and lay members who supported the friars' work.

The Cathars, also called the Albigenses, brought back an old heresy known as Gnosticism. They taught that the physical world was evil and that only spiritual things were good. The Cathars became influential in parts of France and caused concern for the Catholic Church. The Waldensians and the Cathars grew strong in the Alps, where central authority was weak. They also spread into cities in France and Italy.

Many of their followers were educated and respected. Local clergy often found it difficult to argue against them. Because of this, the Dominicans were formed to respond. They focused on education and trained priests to explain and defend Catholic teaching. In Spain, the Dominicans also helped lead the Spanish Inquisition. They questioned Jews, Muslims, and others accused of heresy.

Thomas Aquinas (1225–1274) was one of the most famous Dominican friars in history. He was a leading thinker in the Middle Ages. He studied theology and philosophy with Albert the Great at the University of Cologne. He wrote the Summa Theologica, which became a standard textbook for theology in the Middle Ages. His work included many of the newest ideas in philosophy and science at the time.

Aquinas brought Aristotle's ideas back into the Western church and helped articulate arguments for God’s existence. He argued that the order and detail of the universe pointed to an intelligent creator as its cause. Aquinas showed the Dominican focus on study, care for others, and simple living. In 1567, Pope Pius V named him a Doctor of the Church for his important work in theology and philosophy.

During the Protestant Reformation, the Dominicans worked with the Catholic Church to correct abuses and respond to Protestant teachers. The Society of Jesus, a new order, helped the Dominicans defend Catholic teaching. The Dominicans also joined the Jesuits in sharing their faith with people in Spain’s empire in the Americas. In Europe, they helped improve the training of clergy. In 1577, the Catholic Church founded a university in Rome to train Dominican theologians—the Pontifical University of Saint Thomas Aquinas, also called the Angelicum.

Today, the Dominicans continue their work. In 2026, the Dominican Order has more than 5,000 friars in many countries. Their life is based on four main practices: prayer, study, community life, and preaching. Dominican friars serve as professors in Catholic universities, missionaries in other countries, and university chaplains. Their writings can often be recognized by the letters “O.P.” after their names (for the Order of Preachers), but their main work is still preaching.