The movement began with the reforms that Abbot Armand Jean le Bouthillier de Rancé introduced in 1664, later leading to the creation of Trappist congregations, and eventually the formal constitution as a separate religious order in 1892.

Armand Jean le Bouthillier de Rancé, originally the commendatory abbot of La Trappe, led the reform.

As commendatory abbot, de Rancé was a secular individual who obtained income from the monastery but was not a professed monk and otherwise had no monastic obligations.

The second son of Denis Bouthillier, a Councillor of State, he possessed considerable wealth and was earmarked for an ecclesiastical career as coadjutor bishop to the Archbishop of Tours.

[3][4] De Rancé's reform was first and foremost centered on penitence; it prescribed hard manual labour, silence, a meagre diet, isolation from the world, and renunciation of most studies.

[5] In 1892, seeking unity among the different Trappist observances, the Trappist congregations left the Cistercian Order entirely and merged to form a new order with the approval of Pope Leo XIII named the 'Order of Reformed Cistercians of Our Lady of La Trappe', formalising their identity and spirituality as a separate monastic community.

[7] A well-known Trappist theologian was Thomas Merton, a prominent author in the mystic tradition and a noted poet and social and literary critic.

He entered the Abbey of Gethsemani in 1941 where his writings and letters to world leaders became some of the most widely read spiritual and social works of the 20th century.

Merton's widely read works include his autobiography, The Seven Storey Mountain, as well as New Seeds of Contemplation and No Man is an Island.

His defining characteristic was his intense devotion to a religious life and personal piety despite the setbacks of his affliction with diabetes mellitus.

Benedict's precept to minimize conversation means that Trappists generally speak only when necessary; thus idle talk is strongly discouraged.

[10] Unlike the Benedictines and Cistercians,[11][12] Trappists fully abstain from "flesh meats" (pig, cattle, sheep, venison, etc), described by Saint Benedict as "four-footed animals".

[13] However, they generally do not live as strict vegetarians, as they consume poultry, fish and seafood, though their diet mostly consists of vegetables, beans, and grain products.

[24] The Trappist monks of the Tre Fontane Abbey raise the lambs whose wool is used to make the pallia of new metropolitan archbishops.