a 19th- and 20th-century effort in Christian churches to restore the active and intelligent participation of the people in the liturgy, or official rites, of the Christian religion. The movement sought to make the liturgy both more attuned to early Christian traditions and more relevant to modern Christian life. The process involved simplifying rites, developing new texts (in the case of Roman Catholicism, translating the Latin texts into the vernacular of individual countries), and reeducating both laity and clergy on their role in liturgical celebrations. The Liturgical Movement made use of patristic and biblical studies, Christian archaeology, and the increased availability of early Christian literature and liturgical texts.

In the Roman Catholic Church, the movement can be traced back to the mid-19th century, when it was initially connected with monastic worship, especially in the Benedictine communities in France, Belgium, and Germany. After about 1910, it spread to Holland, Italy, and England and subsequently to the United States. About the time of World War II, the movement spread into parishes and became more pastoral in tone in France and Germany. Revisions of liturgy attempted to bring the rites more in accord with early Christian liturgical understanding and practices and yet to take into account the present needs of church members. Early changes included an emphasis on frequent reception of communion at mass and some revisions in the church calendar.

Pope Pius XII played a significant role with the 1947 encyclical Mediator Dei, in which he stressed the importance of liturgy and the need for people to participate. The actual reform of rites began with Holy Week revisions in 1951 and 1955. The second Vatican Council (Vatican Council, Second) (1962–65) endorsed the aims of the movement and recommended that Roman Catholics should actively take part in the liturgy; legislated the use of the vernacular for liturgies, overturning the traditional use of Latin as the sole liturgical language; and ordered the reform of all sacramental rites, a task completed in the 1970s. A new lectionary and calendar (the Ordo Missae) appeared in 1969, and a definitive Roman Missal was published in 1970.

Protestant churches have also revised texts and updated archaic expressions in their liturgical rites, often taking advantage of the broader ecumenical studies. The United Presbyterian Church (Presbyterian Church (U.S.A.)) published a liturgy for congregational use, the Worshipbook, in 1970. In 1978 the Lutheran Church in the United States published its revised Lutheran Book of Worship, offering more individual choices in liturgy and also an expanded variety of musical styles. In 1979 the Episcopal Church (Episcopal Church in the United States of America) adopted a revised Book of Common Prayer, which offered a choice of texts, one preserving the traditional language.