The 81-year-old pope, appearing in relatively good form, ushered in one of Christianity's most joyous holidays during a midnight Mass inside St. Peter's Basilica, which glistened with flashbulbs and floodlights.
During the Mass, televised live to 47 countries around the world, a prayer urged Christians, Jews and Muslims to "try everything possible so that the name of God is not exploited for works of death"--a reference to terrorism.
Outside, police searched pilgrims' bags and purses and used metal-detecting wands as part of the Vatican's anti-terrorism security.
While the Italian media have said the Vatican is a prime terrorist target following the Sept. 11 attacks, security measures resembled those taken during the past two Christmas holidays.
John Paul opened this year's Christmas celebrations by lighting a single candle in the window of his apartment overlooking St. Peter's Square last night - a silent vigil for peace that has been a hallmark of his 23-year papacy.