It is the seat of the Archbishop of Saint Andrews and Edinburgh and the mother church of Scots Catholicism.

The Chapel of St Mary's was opened in 1814 and was originally designed by James Gillespie Graham.

It was built in replacement of the Chapel of St Andrew the Apostle on Blackfriars Wynd (which had been tolerated despite Scotland not recognising the Catholic faith).

[3] The church was considerably embellished over the years, and in 1878 (upon the restoration of the Scottish hierarchy), it became the pro-cathedral of the new Archdiocese of St Andrews and Edinburgh.

[7] The Schola Cantorum has eight singers and sings a wide range of sacred music including plainchant, renaissance polyphony and modern compositions.