Past pontiffs have used the Sunday window greetings to offer brief reflections and wishes in several languages.
Vatican spokesman the Rev. Federico Lombardi said Francis would likely stick with Italian, a language he's comfortable with for spontaneous remarks. Lombardi left open the possibility the 76-year-old pope would use other languages in future public appearances.
During his window speech, Francis also talked about of his family's roots in Italy's northwestern Piedmont region. He told the crowd that by naming himself as pope after St. Francis of Assisi, an Italian patron saint, he was "strengthening my spiritual tie with this land, where, as you know, my family has its origins."
The crowd was cheering wildly when Francis appeared at the window, but fell into rapt silence when he began to speak. Some people's eyes welled up. Many people waved the blue-and-white flag of Argentina, the pope's homeland. Some people held their children aloft or on their shoulders to get a better look.
"We are so proud. He is Argentine, but also belongs to the rest of the world," said Ivana Cabello, 23, of Argentina.
Angela Carreon, a 41-year-old Rome resident originally from the Philippines, ventured that Francis "looks like John Paul II. "
"I hope he is like him," she said. "He has a heart."
The globe-trotting Polish-born John Paul II, who died in 2005, loved to charm the crowds.
Several hundred extra traffic police were deployed Sunday to control crowds and vehicles for Francis' first window speech as well as the annual Rome marathon. Bus routes were rerouted and many streets were closed off to channel the curious and the faithful up the main boulevard from the Tiber river to St. Peter's Square.
Giant video screens were set up so the huge crowd could get a close look at Francis, and dozens of medical teams were on hand for any emergencies. In the last hour before noon, a large backup formed of people trying to squeeze through three openings in the fence ringing the front of the square. But by the time Francis appeared, all had calmly found a viewing spot.
Among Francis' first formal meetings is an appointment Monday with Argentine President Cristina Fernandez. That will provide an opportunity to see if the new pope's easygoing manner still holds — the two have been on opposite sides for many years. As Buenos Aires archbishop, Francis had lobbied hard against the government's move to legalize gay marriage and make contraceptives available for free.
On Tuesday, Fernandez will join other world leaders and senior international envoys, including U.S. Vice President Joe Biden and the president of Jesuit-run Georgetown University, for Francis' formal installation as pope.
Associated Press writers Daniela Petroff and Karl Ritter contributed to this report.