This thesis assesses the political life of Brendan Corish, (1918-90), who was a Labour TD for Wexford from 1945 up until his retirement in 1982. He first entered politics in the December 1945 by-election, which was held due to the death of his father, Richard Corish, (1886-1945). His father played a major role in the local Labour movement and was also TD and Mayor of Wexford. Hence, the mantle of responsibility was great. Three years after entering Leinster House, Corish was promoted as Parliamentary Secretary to the Ministers for Local Government and Defence in the first Inter-Party Government, (1948-51). The coalition government was dissolved three years later. In 1954, he became Minister for Social Welfare in the second Inter-Party Government, (1954-7). The thesis demonstrates that Corish’s second experience of coalition government was negative overall and as a result, he was adamant that Labour would not enter another coalition. In 1960, Brendan Corish was elected party leader. Under his guidance, Labour was completely transformed. The party became radical, socialism was adopted, new policies were developed and new recruits were enlisted. After an improved performance by Labour in the general elections of 1961 and 1965, Corish predicted that a majority Labour Party government would be elected in 1969. However, the party actually lost four seats. In 1970, he proposed the motion, which called for the reversal of Labour’s anti-coalition stance. This motion was accepted. Labour and Fine Gael made preparations for a new government. In 1973, Corish became Tánaiste and Minister for Health and Social Welfare in the National Coalition, (1973-7). While in charge, he introduced key reforms. However, the government was faced with economic and security crises. In 1977, Labour and Fine Gael were voted out. As a result, Brendan Corish stepped down as leader and he retired from politics in 1982. This thesis examines the contribution that Brendan Corish made to Irish political life over a long and varied career in politics. It looks at the transforming image of socialism in Ireland, Corish’s legacy on the Irish Labour Party, the impact of religion on his politics, as well as the effect politics had on his family and personal health.