Pope Francis has officially begun his ministry as the 266th pontiff, receiving the ring symbolising the papacy and a wool stole symbolising his role as shepherd of his 1.2-billion strong flock.
A cardinal intoned the rite of inauguration at the start of the Mass, saying: "The Good Shepherd charged Peter to feed his lambs and his sheep; today you succeed him as the bishop of this church."
Later half a dozen cardinals approached the Argentine-born pope to pledge their obedience.
The installation occurred in sun-drenched St Peter's Square in front of tens of thousands of people, princes, sheiks, rabbis and presidents.
