He was born in 1932 in Leitrim Middle, Moyvane (formerly Newtownsandes), north Kerry into a family immersed in Irish traditional music.

Pat learnt the fiddle from his mother, and Irish step-dancing from the famous Kerry dance master Jeremiah Molyneaux.

[1] Pat attended primary school in Moyvane (1938–1944), subsequently enrolling at St Michael's College, Listowel (1944–1948).

He was ordained in 1957, and that year appointed curate in St. John's Parish Tralee, County Kerry, with special responsibility for liturgical music.

In 1972, at the request of Éamonn Casey, Bishop of Kerry, and Brendan O'Regan, Chairman of Bórd Fáilte, the Irish Tourist Board, a ten-year plan was drawn up by Ahern for the development of the Tralee folk theatre, now known nationally as Siamsa Tíre.

[7] The following year Bishop Casey recalled Ahern from Dublin to Kerry, and released him from diocesan commitments to work full-time on the new folk theatre project in Tralee.

[8] In 1974 Siamsa Tíre was incorporated as a company, funded by Bord Fáilte, the Irish Tourist Board, and by Roinn na Gaeltachta (the government department for Irish-speaking districts); Pat Ahern was artistic director and Martin Whelan the manager until his death in 2002.

Ahern's aim: "To provide through the medium of the theatre an attractive means of accessing our rich cultural heritage.

… The Irish language enshrines a vast reservoir of story, poetry and song that is unique among the cultures of the world.

[11] The significance of Siamsa Tíre was summed up by the writer Frank Delaney in 1976 just before the company's first tour to the United States: