St Mary's College (Welsh: Coleg Mair) was a Roman Catholic seminary in Aberystwyth, Wales, in the United Kingdom.

[1] In 1936, the Bishop of Menevia, Michael McGrath invited the Carmelites to reopen the college in Aberystwyth and staff the local church of Our Lady of the Angels and St Winefride.

[3] One noted teacher there from 1936 was Saunders Lewis, he worked with Fr Geary, and one of their pupils was the poet John Fitzgerald.

[4] After World War II, the Carmelites realised that an expansion was needed, so some of the staff and students were moved to set up a minor seminary in Tregib Manor in Llandeilo and the college in Aberystwyth was to become focussed on the training of mature students for the priesthood.

In 1970, St Mary's College was also closed and the building was bought by the Welsh Books Council who continue to reside there.