
A century later, Paul III created Girolamo Aleandro a cardinal on 22 December 1536 and published his name on 13 March 1538.

Under pressure to maintain a delicate network of alliances in the last years of Western Schism, beginning in 1423 Martin V withheld the names of some he created cardinals, the first in pectore appointments. In the early history of the College of Cardinals, all cardinals appointed were published as a matter of course. Should the pope die without publishing an appointment he has made in pectore, the appointment lapses. The announcement allows the cardinal to receive and wear the symbols of his office, use the titles appropriate to his rank, and to perform the functions specific to a cardinal, most importantly, if otherwise qualified, to participate in a papal conclave. This reflects the principle that he has been a cardinal from the earlier date and that membership in the College of Cardinals depends on the decision of the pope, not any ceremony or ritual. Once his appointment is published, the precedence of a cardinal appointed in pectore is determined by the date of the appointment, not the announcement.

Over the centuries, popes have made in pectore appointments in consideration of government and political relations in a wide variety of nations, from Portugal and several European states to the Soviet Union and the People's Republic of China. Since the fifteenth century, popes have made such appointments to manage complex relations among factions within the Church, when publication of a new cardinal's name might provoke persecution of the individual or of a Christian community or, when the identity of the new cardinal is an open secret, to signal defiance of government opposition or stake out a diplomatic or moral position. In the first half of the 19th century, Pope Gregory XVI appointed half of his 75 cardinals in pectore and left several unidentified at his death. Some popes have used it rarely or not at all, while others have used it regularly. Since the practice arose in the sixteenth century its use has varied greatly.

When the name of a new cardinal is announced or made public, it is sometimes said to be published. The Italian language version of the phrase – in petto – is sometimes used. It is most often used when there is a papal appointment to the College of Cardinals without a public announcement of the name of that cardinal. In pectore ( Latin for "in the breast/heart") is a term used in the Catholic Church for an action, decision, or document which is meant to be kept secret.
