The keynote guest - the pope himself - has already been announced, as have an official prayer and icon.

On Sunday, Archbishop Charles J. Chaput checked off yet another box on the list of preparations for next year's World Meeting of Families: the debut of an official hymn.

"Sound the Bell of Holy Freedom," commissioned from liturgical composer Normand Gouin, was sung for the first time Sunday at a Mass that Chaput celebrated at the Cathedral Basilica of SS. Peter and Paul.

Gouin, now at the College of the Holy Cross in Worcester, Mass., is a former music director at Old St. Joseph's Church in Society Hill.

Those in attendance Sunday also received copies of the conference's official icon blessed by Chaput, archdiocesan officials said. The image, painted by Kennett Square artist Neilson Carlin, depicts Jesus as a toddler surrounded by Mary and Joseph and Mary's parents, SS. Anna and Joachim. The archdiocese presented it and the conference's official prayer in September.

Sunday's service marked the first of the Advent season as well as the first time Chaput has celebrated Mass at the basilica since Pope Francis confirmed he planned to attend the September conference.

The five-day World Meeting of Families is scheduled to begin Sept. 22 and is expected to draw more than a million people for a chance to witness what will be the pope's first visit to the United States since his election last year.