The Roman Missal (Latin: Missale Romanum) is the liturgical book that contains the texts and rubrics for the celebration of the Mass in the Roman Rite of the Catholic Church.

Before the high Middle Ages, several books were used at Mass: a Sacramentary with the prayers, one or more books for the Scriptural readings, and one or more books for the antiphons and other chants. Gradually, manuscripts came into being that incorporated parts of more than one of these books, leading finally to versions that were complete in themselves. Such a book was referred to as a Missale Plenum (English: "Full Missal"). In 1223 Saint Francis of Assisi instructed his friars to adopt the form that was in use at the Papal Court (Rule, chapter 3). They adapted this missal further to the needs of their largely itinerant apostolate. Pope Gregory IX considered, but did not put into effect, the idea of extending this missal, as revised by the Franciscans, to the whole Western Church; and in 1277 Pope Nicholas III ordered it to be accepted in all churches in the city of Rome. Its use spread throughout Europe, especially after the invention of the printing press; but the editors introduced variations of their own choosing, some of them substantial. Printing also favoured the spread of other liturgical texts of less certain orthodoxy. The Council of Trent recognized that an end must be put to the resulting confusion.