This chapter provides the first dedicated study of the Irish National League, founded by former MPs Capt. Redmond and Thomas O’Donnell in 1926. Analysing the categorisation of the League as a ‘mobilising’ party, this chapter argues that it was, in fact, a ‘legacy party’, illustrating how the League drew on the old Irish Party personnel, slogans and ephemera. While statistical data highlights the home rule connections of TDs standing for each party, there is also analysis of the League’s controversial actions during the tumultuous summer of 1927, examining two general election campaigns, the aftermath of Kevin O’Higgins’s assassination and the League’s failed attempt to form a coalition government with Labour following the entry of Fianna Fáil into the Dáil. It is argued that despite its short life span, the League was significant in Irish politics as it not only came within a casting vote of government but helped to accelerate the assimilation of former home rule supporters into new parties.