This thesis provides a broad history of the Irish Press during the years 1919-1948. It sets forth how, from 1919 onwards, Republican leader Eamon de Valera became convinced of the need for a newspaper sympathetic to his aims, and how he went about raising funds for the enterprise both in Ireland and the United States. The corporate structure of the Irish Press is also examined, with particular emphasis on the role of the Controlling Director and the influence of the Irish Press American Corporation. The Irish Press was first published in 1931, and the thesis examines its support for Fianna Fail in the period under study. The work also examines the changes in the relationship between the party and the paper as Fianna Fail became more entrenched in government. The role of the first editor of the Irish Press. Frank Gallagher, is considered. The changes in the attitude of the Irish Press to Fianna Fail in the post-Gallagher period are also examined, with emphasis on the findings of the Fianna Fail sub-committee on publicity. The thesis concludes that the period under review was characterised by the emergence of four key elements in the culture of the Irish Press: volatile industrial relations climate, fund-raising problems, links to Fianna Fail, and a corporate structure which ensured dynastic control by the de Valera family.