Taking the name Francis, after the saint who ministered to the poor, Argentine Jorge Mario Bergoglio, the first Latin American to lead the Catholic Church, has earned a reputation for living the simple, quiet life of his namesake.
Bergoglio, 76, is the first Jesuit to become pope, and was the archbishop of Buenos Aires, where he has criticized Latin priests whom he calls "hypocrites" for refusing to baptize children born out of wedlock.
He becomes the 266th pope and the first pontiff in more than a millennium to be born outside of Europe.
He made a name for himself leading a simple life, preparing his own meals, living in a Spartan apartment and riding public transportation, all the while eschewing the luxurious mansion in which he was entitled to live.
Bergoglio was in 2005 considered a runner-up to Pope Benedict XVI, who resigned earlier this month.
Although not considered a liberal, he is seen as a reformer who has made social justice a priority in his ministry.
In criticizing the priests who refused to baptize out-of- wedlock children, he argued that their mothers had done the right thing by not receiving abortions and should not be shunned by the church.
Priests who refused to perform such baptisms "drive God's people away from salvation," he said.
Bergoglio told his priests: "In our ecclesiastical region, there are priests who don't baptize the children of single mothers because they weren't conceived in the sanctity of marriage.
"These are today's hypocrites. Those who clericalize the church. Those who separate the people of God from salvation. And this poor girl who, rather than returning the child to sender, had the courage to carry it into the world, must wander from parish to parish so that it's baptized."
Despite the authority of the church in Latin America, Bergoglio was not influential enough to stall lawmakers in Argentina from recently legalizing gay marriage. He has in the past argued that gay parents should not be allowed to adopt children.
The Jesuits have traditionally been considered too "critical of the church hierarchy" to ascend to the papacy, said the Rev. James Martin, the editor of "America" and a Jesuit.
Jesuits are known for being the intellectuals among the priests. They run top colleges and schools, are defenders of traditional liberal arts curriculum and academic-scientific research, and tend to be more liberal than the other orders.
Bergoglio is one of five siblings. His father was a railroad worker, born in Italy.
As a teenager, he had a lung removed after an infection.
He has been archbishop of Buenos Aires since 1998.