Denis Gallagher was born in Currane, by Clew Bay, facing Achill Island, County Mayo in 1922, the son of John Gallagher, a merchant, and his wife Catherine (née Gallagher). He grew up speaking English and Irish.[2] He was educated locally and at Coláiste Éinde in Salthill. He qualified as a national school teacher having graduated from St Patrick's College in Drumcondra, Dublin. He taught in Drimnagh in Dublin for several years before returning to Mayo in 1946 to take up a teaching post. He married Hannah McHugh of Keel West, Achill in 1948, and they had twelve children.[2]
Fianna Fáil returned to government in March 1982. In October 1982, following the resignations of Martin O'Donoghue and Desmond O'Malley from the cabinet, Gallagher returned as Minister for the Gaeltacht.[6] He remained in that post until December when Fianna Fáil went into opposition.
