Little Office of Our Lady
The Little Office of Our Lady also known as Hours of the Virgin is a liturgical devotion to the Blessed Virgin Mary, in imitation of, and usually in addition to, the Divine Office in the Roman Catholic Church (Some secular orders did use the Little Office on its own as their official form of prayer). It is a weekly cycle of psalms, hymns, scripture and other readings.
All of the daily variation occurs in Matins (which is usually said with Lauds). The text of the other offices (Prime to Compline) remains the same every day in the Roman rite and most other rites. In the Roman rite there are seasonal variations in Advent and Christmastide. The Gospel antiphon also changes in Eastertide, although there are no other changes during that season. The Little Office was a core text of the medieval book of hours.
The Little Office of the Blessed Virgin Mary probably originated as a monastic devotion around the middle of the eighth century. Peter the Deacon reports that at the Benedictine Monastery of Monte Cassino there was, in addition to the Divine Office, another office "which it is customary to perform in honour of the Holy Mother of God, which Zachary the Pope commanded under strict precept to the Cassinese Monastery." 
The Little Office of the Blessed Virgin Mary is a variation of the Common of the Blessed Virgin Mary in the Liturgy of the Hours (Divine Office). It may have originally been put together to be prayed in connection with the Votive Masses of Our Lady on Saturday, which were written by Alcuin, the liturgical master of Charlemagne’s court.
Peter Damian states that it was already commonly recited amongst the secular clergy of Italy and France, and through his influence the practice of reciting it in choir after the Monastic Office, was introduced into several Italian houses. However, the Little Office did not come into general use before the tenth century; and in the eleventh century there were at least two versions the Little Office extant in England. Pre-English Reformation versions varied considerably, and in England in medieval times the main differences were between the Sarum and York uses. Several early printed versions of the English uses of the Little Office survive in the Primers.
In the twelfth century, the new foundation of the Augustinian (Austin) Canons of Prémontré prescribed the Little Office in addition to the eight hours of the Divine Office. The Austin Canons also used it, and, perhaps through their influence, it developed from a private devotion into part of the daily duty of the secular clergy as well in the thirteenth and fourteenth centuries. By the fourteenth century the Little Office was obligatory for all the clergy. This obligation remained until St. Pius V changed it in 1568. The Little Office varied in different communities and locations, but was standardized by Pius V in 1585. It became part of the Books of Hours in Mary’s honor and was used by many lay people. Beautifully decorated Books of Hours were the pride of many a noble. Women’s congregations and Third Orders often made it mandatory for their members to pray the Little Office.
Down to the Reformation it formed a central part of the "Primer" and was customarily recited by the devout laity, by whom the practice was continued for long afterwards among the persecuted Catholics. An English-only version appears appended to versions of Bishop Richard Challoner's 'Garden of the Soul' in the eighteenth century, and with the restoration of the hierarchy in the 1860s, James Burns issued a Latin and English edition.
Minor revisions of the Office occurred in the twentieth century, most notably in 1910, as part of Pope Pius X's liturgical reforms. The most significant change made by the pontiff was the shortening of the numbers of psalms recited at Lauds from seven to four (excluding the canticle).
"20. Although Religious who recite a duly approved Little Office perform the public prayer of the Church (cf. Constitution Sacrosanctum Concilium, No. 98), it is nevertheless recommended to the institutes that in place of the Little Office they adopt the Divine Office either in part or in whole so that they may participate more intimately in the liturgical life of the Church...."
The Little Office was not officially revised after the Council, as many Congregations abandoned it in order to adopt the Liturgy of the Hours. However, that has not stopped several post-conciliar editions being issued. The Carmelites produced a revised version of their form of the office, which is still used by some Religious and those who are enrolled in the Brown Scapular. Additionally Tony Horner, a layman, and Father John Rotelle, O.S.A. both formulated their own editions of the Little Office which conformed to the revised Liturgy of the Hours, both of these are approved for private use. These newer versions include vernacular translations from the Latin and follow the new structure of each Hour in the Office.
Despite its decline among religious orders after the Council, the traditional Little Office in English and Latin has never been out of print. From the 1970s onwards Carmel Books in the UK kept the traditional version in print, and several other publishers also issued editions, usually containing the text as it was in the 1950s. St Bonaventure Publications publish the 1904 edition, which gives the office as it was before Pius X's revisions. The 1961 text, which is the one permitted by Pope Benedict XVI's motu proprio summorum pontificum in 2007, was published for the first time in a bilingual English and Latin edition by Baronius Press later that same year. This edition collected all the Gregorian chant for the office for the first time in a published edition.