Archbishop Wilton D. Gregory will be installed as the seventh archbishop of Washington on May 21 at 2 p.m. during a solemn liturgy at the Basilica of the National Shrine of the Immaculate Conception.

The Mass of Installation will begin with a procession of participating cardinals, archbishops, bishops, priests, deacons and others at 1:30 p.m.

While the Cathedral of St. Matthew the Apostle is the “mother church” of the Archbishop of Washington, archdiocesan officials decided to hold the installation of Archbishop Gregory at the Basilica of the National Shrine of the Immaculate Conception, the largest Roman Catholic Church in North America.

An archdiocesan statement noted that “as the planning for the Mass of Installation began, both Cardinal (Donald) Wuerl and Archbishop Gregory desired that the faithful of the Archdiocese of Washington be able to attend the Mass.”

Seating “is limited in St. Matthew’s and in order to accommodate the large number of laity who expressed interest in attending, the decision was made to move the Mass to the Basilica of the National Shrine of the Immaculate Conception,” the archdiocese said in the statement.

During the Mass, Archbishop Gregory will formally take canonical possession of the archdiocese.

Archbishop Christophe Pierre, the apostolic nuncio to the United States, will read the decree from Pope Francis formally naming Archbishop Gregory as the ordinary of this archdiocese. The nuncio will then ask Archbishop Gregory whether he is willing “to serve almighty God and the people of the Archdiocese of Washington in faith and in love as their shepherd.”

Once Archbishop Gregory accepts, he will be escorted to the cathedra, the bishop’s chair, and will be presented with a crosier and miter. They are symbols of his teaching authority and signs that he has taken possession of the archdiocese.

Prior to the reading of the decree, Cardinal Wuerl will address the faithful gathered for the Mass.

After taking canonical possession, Archbishop Gregory will be greeted and welcomed by various representatives of the archdiocese.

To highlight the diversity of the faithful of the Archdiocese of Washington, the readings for the Mass will in both English and Spanish, and the Prayers of the Faithful will be offered in English, French, Vietnamese, Tagalog (one of several Filipino languages), Igbo (the language of natives of southeastern Nigeria), Chinese, American Sign Language and Spanish.

The Mass will be broadcast on Eternal Word Television Network (EWTN) and live-streamed on social media.

Archbishop Gregory's Mass of installation is open to the public. No tickets are required. Guests are asked to be seated by 1:15 p.m., before the procession.

After Mass, there will be a reception in the basilica’s Memorial Hall downstairs.

The Basilica of the National Shrine is located at 400 Michigan Ave., N.E., with parking available on its lot. The basilica is located near the Brookland/Catholic University of America stop on Metro's Red Line.

Archbishop Gregory will offer a Mass of Thanksgiving on Sunday, May 26, at 10 a.m. at the Cathedral of Saint Matthew the Apostle in Washington at 1725 Rhode Island Ave., N.W., near the Farragut North Station on Metro's Red Line.