The Apostolic Chancery (Latin: Cancellaria Apostolica; also known as the "Papal" or "Roman Chanc(ell)ery") was a dicastery of the Roman Curia at the service of the pope. The principal and presiding official was the Grand Chancellor of the Holy Roman Church, who was always the cardinal-priest of the Basilica di San Lorenzo in Damaso. The principal function of the office was to collect money to maintain the Papal army and to produce documents and correspondence for the pope. Pope Pius VII reformed the office when Emperor Napoleon I of France obviated the need for Papal armies. In the early 20th century the office collected money for missionary work. Pope Paul VI abolished the Apostolic Chancellary on 27 February 1973, transferring its functions to the Secretariat of State.

The role of bibliotecarius first appears in 781, and was responsible for the pope's books as well as redacting documents. The role of cancellarius first appears under Silvester II. The cancellarius produced documents for the pope, while the bibliotecarius would date them. Subsequently, both roles tended to be filled by the same person. The use of the term bibliotecarius ended under Celestine II (1143–1144). From Honorius III (1216–1227) onwards the head of the chancery was called the vicecancellarius.

The Cancellaria Apostolica was of ancient origin in its essence, but it derived its name from that of civil "chanceries", including that of the Imperial Chancery. The primacy of the Roman pontiff required that he have in his service officials to write and transmit his answers to the numerous petitions for favours and consultations addressed to him. Throughout its duration the office was reformed numerous times.

The Apostolic constitution Etsi ad Singula of Pope Clement VII of 5 July 1532 provided the cardinalatial title of the Basilica di San Lorenzo in Damaso to the chancellor.

After Pope Martin V had instituted a large number of offices in the Cancellaria, Pope Sixtus V placed many of them in the class of "vacabili", i. e. venal offices (a practice also of secular courts, e. g. those of France, even under the absolutist King Louis XIV). The reclassification of many of the offices of the Cancellaria as vacabili was motivated by the need of the pope for money. The pope was often compelled to defend the Church by waging war, equipping martial expeditions, or at least financially assisting the princes who waged such wars at his exhortation, but the Papal treasury was often insufficient to defray even the expenses of the Papal States. Accordingly, the popes resorted to the expedient of selling several lucrative offices of the Roman Curia to the highest bidder; however, these sales were not of the offices per se, but of the receipts of the offices, e. g., the taxes paid for the favours that were granted through the pertinent office.

Some of the offices that Pope Sixtus V classified as vacabili were of minor importance and therefore did not require special competence were sold with a grant of the right of succession to the heirs of the purchaser. Offices that entailed grave obligations and for which only pious and learned men were eligible were sold without this right and therefore reverted to the Roman Curia on the death of the purchaser. An aleatory contract, therefore, was formed, its uncertainties being the amount of the income of the office and the length of the life of the purchaser. The prices of the offices, especially of the more desirable ones, were considerable: Lorenzo Corsini, afterwards Pope Clement XII, bought the office of regent of the Cancellaria for 30,000 Roman scudi, a large fortune at the time. The disadvantage of these uncertainties might not be confined to the purchaser because he was free to condition the purchased office on the life of another designated person, named the "intestatary". The purchaser was also permitted to substitute a different intestatary if this substitution was expressed 40 days before the death of the immediately preceding intestatary.

Other offices that Pope Sixtus V classified as vacabili were of greater importance, including that of Regent and those of the 25 solicitors, 12 notaries, and auditors of the Causes of the Holy Palace. Pope Sixtus V assigned the liberal proceeds of these sales as part of the remuneration of the cardinal vice chancellor of the Cancellaria (see below), but later Pope Innocent XI rescinded them and assigned the revenue to the Apostolic Camera. Pope Alexander VIII restored the revenue to the vice chancellor, who at that time was his nephew Pietro Ottoboni.

The authority of the vice chancellor increased when in 1690 Pope Alexander VIII added to his office that of Compiler (Sommista) in perpetuity.