The instituted acolyte is a lay minister who serves two roles in the sacred liturgy. These roles are subdeacon and acolyte: the latter, most precisely, as crucifer. Following from these two basic roles, the instituted acolyte may also serve certain other functions in the Church's liturgical celebration. The roles of the instituted acolyte include:

• Subdiaconal Ministry at mass - assisting the deacon and celebrant at mass as a third sacred minister, essentially performing the role previously filled by subdeacons when they existed as a minor order in the Church.

• Epistoler - reading the epistle, typically at more solemn celebrations

• Extraordinary minister of Holy Communion - ministering the Body and Blood at the Communion of the Faithful.

• Master of Ceremonies at Mass - overseeing the altar servers during mass

• Master of Ceremonies to the Bishop - attending to the Bishop during mass

• Verger - leading liturgical processions at mass or on other occasions

• Officiant at Adoration - leading an Adoration service (but not Benediction) when neither a priest or deacon is present

• Officiant at the Divine Office - leading morning prayer or evening prayer when neither a priest or deacon is present

Servers filling the role of acolyte must be instituted as acolytes by the Bishop.

The acolyte, when in the subdiaconal role or when acting as crucifer wears a liturgical vestment (called a tunicle) in the liturgical color of the day.

The Bishop's Letter on Instituted Acolytes explains the ministry in the Ordinariate.

This role was formerly referred to by the title "clerk". That has been replaced with acolyte upon the institution of acolytes in the Ordinariate to perform this role.