VATICAN CITY -- Pope Francis celebrated his election Thursday by leading his first mass with the cardinals who selected him.
They walked into the Sistine Chapel around 12 p.m. EDT.
The cardinals and the new pope all wore simple yellow robes over their cassocks.
Pope Francis blessed the altar as mass got under way, and spoke about the importance of staying true to the church during the rebuilding process.
"And when we walk without the cross, when we build without the cross and when we confess to a christ without the cross, when we are not really disciples of the Lord. We are worldly. We may be priests, bishops, cardinals, the pope, everything but we are not really disciples of the Lord," Francis said.
The pope then celebrated the Holy Eucharist with the cardinals.
He is expected to pay a personal visit to his predecessor, Pope Emeritus Benedict XVI, in the coming days.
Throughout Rome, news of the new supreme pontiff had many people on the streets talking about a breath of fresh air sweeping the Vatican.
"He's very, very...like the people," said one worshiper.
"I think he's a very, a true image of a chief of the church. Not a monarch or king," said another worshiper.
The 76-year-old Argentine received the required two-thirds majority vote from his fellow cardinals on the second day of the conclave Wednesday.
He was greeted by roaring crowds as he emerged on the balcony at St. Peter's Basilica after the announcement.
Bells rang and thousands cheered in St. Peter's Square.
The new pope addressed the faithful, led them in prayer and asked them to pray for the lord to bless him, adding, "It's a journey of brotherhood and trust among us. Let us pray always for us, let us pray, always for us, one for the other, each one for one another. Let us pray for the entire world."
Pope Francis becomes the first pope from the Americas.
The last non-European pope was Syria's Gregory III, who served until the year 741.
Francis will now have the job of leading the world's 1.2 billion Roman Catholics, including more than two million in New York City.
New York Cardinal Timothy Dolan issued a statement after the announcement calling the election a great milestone for the church, saying intense prayer surrounded the election of Pope Francis.
Speaking with reporters, Dolan was asked if he felt a sense of relief after the vote, since rumors had surfaced he might be selected as pope.
"I wouldn't say there's a sense of relief because I didn't take those things seriously. I'd like to say this especially to the New York press - I told you so," Dolan said.
Pope Francis, who hails from Buenos Aires and is of Italian descent, was ordained in 1969, appointed bishop in 1992 and cardinal in 2001.
He is the first Jesuit pope, and holds many views in line with the church, opposing abortion and same sex marriage.
But he has displayed sympathy for people with drug additions and AIDS, and considers social outreach essential to the church.
As cardinal, he refused many luxuries associated with the job, living in an apartment rather than the archbishop's palace.
He often rode the bus to work and cooked his own meals.
Francis was widely believed to have finished second when Pope Benedict XVI was elected in 2005.
The name Francis he chose as his papal title was inspired by Saint Francis of Assisi, known as a symbol of peace, poverty and simplicity.