Born in Spiddal, Co. Galway. As a writer, O Cadhain is acknowledged to be a pioneer of Irish-language modernism. He was a prolific writer of short stories. His collections of short stories include Cois Caolaire, An Braon Broghach, Idir Shugradh agus Dhairire, An tSraith Dha Togail, An tSraith Togtha and An tSraith ar Lar. He also wrote three novels, of which only Cre na Cille was published during his lifetime. The other two, Athnuachan and Barbed Wire, appeared in print only recently. He also wrote several political or linguo-political pamphlets. He died 18 October 1970 in Dublin.