|Type||Daily official journal|
|Founded||29 September 1908|
Acta Apostolicae Sedis (Latin for "Acts of the Apostolic See"), often cited as AAS, is the official gazette of the Holy See, appearing about twelve times a year. It was established by Pope Pius X on 29 September 1908 with the decree Promulgandi Pontificias Constitutiones, and publication began in January 1909. It contains all the principal decrees, encyclical letters, decisions of Roman congregations, and notices of ecclesiastical appointments. The laws 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.
It was begun in 1865, under the title of Acta Sanctæ Sedis in compendium redacta etc.. Though not designated as the official means of promulgating laws of the Holy See, it was on 23 May 1904 declared an organ of the Holy See to the extent that all documents printed in it were considered "authentic and official". The Acta Sanctæ Sedis ceased publication four years later.
On 29 September 1908, Pope Pius X, in the decree Promulgandi Pontificias Constitutiones, replaced the Acta Sanctæ Sedis with the Acta Apostolicae Sedis, to which he gave the status of the official gazette of the Holy See, and which began publication in January 1909.
Acta Apostolicae Sedis is published in Latin and incorporates documents in many different languages.
Since 1929, Acta Apostolicae Sedis carries a supplement in Italian, called Supplemento per le leggi e disposizioni dello Stato della Città del Vaticano, containing laws and regulations of Vatican City, the city-state founded in that year. In accordance with paragraph 2 of the Legge sulle fonti del diritto of 7 June 1929, the laws of the state are promulgated by being included in this supplement.