The Carmelite order, a Roman Catholic institution, includes priests, religious sisters and brothers, and laypeople dedicated to prayer, community, and service. As one of the four major mendicant orders of the Church, founded in the Middle Ages, the Carmelites traditionally relied on alms due to their shared poverty.

The order originated around 1155 on Mount Carmel in northwestern Israel, where devout men, including former pilgrims and Crusaders, settled near Elijah's traditional fountain. Their rule, written by St. Albert, Latin Patriarch of Jerusalem, between 1206 and 1214, was approved by Pope Honorius III in 1226. These early Carmelites sought to mirror the monastic life of the prophet Elijah.

Originally, hermits living in secluded cells practiced silence, seclusion, abstinence, and austerity. Around 1240, they moved to Cyprus, Sicily, France, and England for safety after the Crusades. In 1247, under St. Simon Stock, the Carmelites transitioned from hermits to mendicant friars at their first general chapter in England, establishing themselves across western Europe like the Dominicans and Franciscans. The first Carmelite nuns' institution was founded in 1452.

Among the Carmelite reforms, St. Teresa of Ávila's was the most significant. After nearly 30 years in a Carmelite convent, she founded a small convent in Ávila, Spain, in 1562, promoting stricter observance and leading to the formation of the Discalced Carmelites.

 The Discalced Carmelites (O.D.C.), with the help of Juan de Yepes (later St. John of the Cross), were established under the reformed practices initiated by St. Teresa. Despite opposition, she founded many convents and friaries adhering to these reforms. The Discalced Carmelites, known as "barefooted" Carmelites, distinguished themselves from the older branch by wearing sandals instead of shoes. In 1580, the reformed monasteries became a separate province under the prior general of the order, and in 1593, they were officially recognized as an independent order by papal decree.

Both branches of the Carmelite order faced major challenges during the French Revolution, Napoleon's suppression, and 19th-century liberal governments but have since experienced a revival in western Europe, the Middle East, Latin America, and the United States. In 2024, Pope Francis canonized 16 Discalced Carmelite nuns and sisters executed during the Reign of Terror in Paris in 1794.

The original Carmelite order (Order of the Brothers of the Blessed Virgin Mary of Mount Carmel; White Friars; O.Carm.) emphasizes preaching and teaching, while the Discalced Carmelite Fathers (Order of Discalced Brothers of the Blessed Virgin Mary of Mount Carmel; O.C.D.) focus on pastoral and devotional activities in parishes and missions. Both branches promote Marian devotion and have seen the growth of numerous Third Order Carmelite congregations, allowing laypeople to participate in teaching, healthcare, and other charitable works inspired by the Carmelite charism.

St. Teresa of Avila: In 1562 Carmelite nun St. Teresa founded a convent in Avila, Spain which became the Discalced Carmelites