He qualified as a national school teacher having graduated from St Patrick's College in Drumcondra, Dublin.

However, Charles Haughey won the election, becoming Taoiseach, and Gallagher lost his position in cabinet.

In March 1980, he was appointed as Minister of State at the Department of Industry, Commerce and Tourism[5] He served in this role until the Fianna Fáil lost office in June 1981.

In October 1982, following the resignations of Martin O'Donoghue and Desmond O'Malley from the cabinet, Gallagher returned as Minister for the Gaeltacht.

After his retirement, he worked to advance the Irish language cause and also served as chairman of the Gaelic Athletic Association in Mayo.