The GIRM, or the General Instruction of the Roman Missal, from the Roman Missal, Third Edition, seeks to promote a more conscious, active, and full participation of the faithful in the mystery of the Eucharist.
The GIRM [often pronounced “germ”] provides specific detail about each element of the Order of Mass as well as other information related to the Mass. The GIRM is the detailed document governing the celebration of Mass of the ordinary form of the Roman Catholic Church.
Stated in no. 1 of the Introduction of the GIRM: “As Christ the Lord was about to celebrate with the disciples the paschal supper in which he instituted the Sacrifice of his Body and Blood, he commanded that a large, furnished upper room be prepared.
Indeed the Church has always judged that this command also applied to herself whenever she decided about things related to the disposition of people’s minds, and of places, rites and texts for the Celebration of the Most Holy Eucharist.”
The Roman Missal contains all the prayers recited at Mass, and the GIRM describes the rubrics, or instructions, on how the Mass is to be celebrated.
Praying the Mass with careful attention to the rubrics enables all Catholics to become “ever more holy by conscious, active, and fruitful participation in the mystery of the Eucharist.” (9:39)