| Type | Monthlyofficial journal |
|---|---|
| Publisher | Vatican City |
| Founded | 29 September 1908; 117 years ago (1908-09-29) |
| Language | Latin (documents published can be in any language) |
| Headquarters | Vatican City |
| ISSN | 0001-5199 |
Acta Apostolicae Sedis (Latin for 'Acts of theApostolic See'), often cited asAAS, is the officialgazette of theHoly See,[1] appearing about twelve times a year.[2] It was established byPope Pius X on 29 September 1908 with the decreePromulgandi Pontificias Constitutiones, and publication began in January 1909.[2] It contains all the principal decrees, encyclical letters, decisions ofRoman congregations, and notices of ecclesiastical appointments.[3] Thelaws contained in it are to be considered promulgated when published, and effective three months from date of issue, unless a shorter or longer time is specified in the law.[3][4][5]
Acta Sanctæ Sedis (ASS; Latin for 'Acts of theHoly See') was a Roman monthly publication containing the principal public documents issued by the pope, directly or through the Roman congregations.[6]
It was begun in 1865, under the title ofActa Sanctæ Sedis in compendium redacta etc.. At the time, it was not designated as the official means of promulgating laws of the Holy See, nor as an official publication of the Holy See; the publication of theASS was purely a private initiative. However, this changed when on 23 May 1904 theAAS was declared an organ of the Holy See by Pius X, to the extent that all documents printed in it were considered "authentic and official"; those dispositions were put in place beginning with vol. 37 of theASS, in 1904.[6][7] TheActa Sanctæ Sedis ceased publication in 1908, with its last volume being the 41st.[7]

On 29 September 1908, Pope Pius X, in thedecreePromulgandi Pontificias Constitutiones, replaced theActa Sanctæ Sedis with theActa Apostolicae Sedis, to which he gave the status of the official gazette of the Holy See, and which began publication in January 1909.[8] In the new disposition, the documents published in theAAS are considered as authentic and official—like the ones in theASS since its volume 37—but the novelty is that it is by the publication in theAAS that those documents, unless otherwise stated, arepromulgated.[9]
TheActa Apostolicae Sedis is published in Latin, but also contains documents in many different languages.
Since 1929,Acta Apostolicae Sedis can have a supplement inItalian, calledSupplemento per le leggi e disposizioni dello Stato della Città del Vaticano, containing laws and regulations ofVatican City, the city-state founded the same year. In accordance with paragraph 2 of theLegge sulle fonti del diritto of 7 June 1929,[10] the laws of the state are promulgated by being included in this supplement.