The College of Cardinals, or more formally the Sacred College of Cardinals, is the body of all cardinals of the Catholic Church. As of 26 March 2023, its membership is 222, of whom 123 are eligible to vote in a conclave to elect a new pope. Cardinals are appointed by the pope for life. Changes in life expectancy partly account for the increases in the size of the college.

Since the emergence of the College of Cardinals in the early Middle Ages, the size of the body has historically been limited by popes, ecumenical councils ratified by the pope, and even the College itself. The total number of cardinals from 1099 to 1986 has been about 2,900 (excluding possible undocumented 12th-century cardinals and pseudocardinals appointed during the Western Schism by pontiffs now considered to be antipopes, and subject to some other sources of uncertainty), nearly half of whom were created after 1655.