Pope Leo XIV's inaugural Mass is filled with symbolism. Here's what you need to know

VATICAN CITY — Pope Leo XIV 's inaugural Mass on Sunday morning in St. Peter's Square and Basilica is a ritual filled with symbolism that connects back to Peter, Jesus' apostle, and his special mission as head of the Catholic Church.

No new role is conferred — the pontiff is already the head of the Vatican and of the faith counting some 1.4 billion Catholics worldwide, tens of thousands of whom gathered in the square for the Mass alongside government representatives.

Leo will receive two crucial signs of his pontificate, the ''pallium'' and the fisherman's ring, marking his role as successor of Peter.

Here's what to know about them and more rituals in the solemn liturgy replete with ancient languages and Scriptural references – all after Leo takes a spin around the square in the popemobile.

What's the inauguration Mass?

In most parts, it's a celebration of the Eucharist just like any Sunday Mass held in Catholic churches around the world.

There will be prayers, music, readings from the New Testament, a homily and Communion, all in the usual order. Symbolism is interwoven even in some of the typical aspects, though.

The Gospel passage, for instance, will focus on Jesus giving Peter responsibility as the shepherd of the church — a reference Leo made in his first public words the day he was elected.

It will be proclaimed first in Latin and then in Greek. As the main languages of the nascent church 2,000 years ago, today they signify ''the church's attempt to reach everyone'' and be universal, said the Rev. Giuseppe Midili, a professor and consultant with the Vatican's liturgy office.

In a more personal touch, the Vatican says that by the outdoor altar there will be an image of the Mother of Good Counsel — an icon of Mary from a sanctuary in a small village outside Rome served by Augustinians, Leo's religious order.

The signs of Peter — a vestment and a ring

Two of the most significant moments will be right before the homily, when cardinals will give Leo the pallium and his fisherman's ring.

The pallium is a narrow stole-like vestment with two pendants to be worn across the shoulders, decorated with crosses representing Jesus' wounds. It's made of white wool in an elaborate procedure where the lambs traditionally were blessed before being sheared, just like for the similar vestments given to archbishops on their ordination.

''It's the symbolism of the good shepherd who carries the sheep on his shoulders,'' Midili said.

''Pastor'' means shepherd in Latin and Scriptures often refer to the good shepherd who gives his life for his flock, a reference to the crucifixion of Jesus, and of Peter, who was martyred. Leo will receive it from Cardinal Dominique Mamberti, who told the world the new pope's name on May 8.

The fisherman's ring recalls the Gospel passage where Jesus appeared to the apostles after his resurrection as they had spent a night fishing with no catch. He told Peter to cast in a specific spot— and the nets strained with lots of large fish, some of which the apostles then shared with Jesus in a lakeside breakfast.

An image of Peter with the net, standing for the church's evangelization mission and its unity, is engraved on the ring alongside the pope's name. When a pope dies, the ring is crossed over so it can no longer be used as seal for papal documents. Cardinal Luis Tagle of the Philippines, who was widely regarded as a papal contender, will present Leo with the ring.

At the beginning of the celebration, both ring and pallium are taken from the chapel of St. Peter's tomb, underneath the Basilica — where the pope prays accompanied by the patriarchs of eastern rite Catholic churches — out to the altar set up in St. Peter's Square.

Meet and greet, from the faithful to world leaders

Just after the giving of those two insignia, a delegation representing different roles in the church, from cardinals to the faithful, including a married couple, will greet Leo in the ''rite of obedience'' that symbolizes the church turning to the new pontiff to follow his guidance.

After Mass, Leo will greet the government representatives, royalty and religious delegations.

U.S. Vice President JD Vance and Secretary of State Marco Rubio, both Catholics representing an administration that often sparred with Pope Francis, are scheduled to attend Mass for the first U.S. pope.

Also expected at Mass, according to the Vatican, are more than 20 heads of state including Italy's president, Sergio Mattarella, and Premier Giorgia Meloni, as well as Dina Boluarte, the president of Peru, where Leo has citizenship and spent many years as missionary and bishop.

The presidents of two countries involved in wars that Leo mentioned in his first Sunday blessing are also on the list — Israel's Isaac Herzog and Ukraine's Volodymyr Zelenskyy.

The king and queen of Spain are planning to attend alongside other royalty from Europe and as well as Gulf kingdoms including Sheikh Saud bin Saqr Al Qasimi of the United Arab Emirates.

___

Associated Press religion coverage receives support through the AP's collaboration with The Conversation US, with funding from Lilly Endowment Inc. The AP is solely responsible for this content.