This thesis offers a contribution to Irish historiography with a study of Ireland’s diplomatic and friendship relations with the Soviet Union in the ‘short Soviet twentiethcentury’. To date no such study has been produced. The study has as its central focus developments surrounding the establishment of formal diplomatic relations between the two states in 1973, and considers aspects of how those relations evolved down to 1980. To provide an understanding of the legacy of relations prior to formalisation of relations, the study commences with a survey of the principal diplomatic contacts from 1919 to 1972, including those that took place in America between representatives of the nascent Irish republic and Soviet Russia during the revolutionary period of 1919-21, contacts between the Irish Free State and the Soviet Union at the League of Nations in the mid- 1930s, and between the Republic of Ireland and the Soviet Union at the United Nations from 1955 to 1972. It proceeds to examine in more detail events surrounding the establishment of formal diplomatic relations in 1973, and experiences during the first six years at the Irish embassy to Moscow, and at the Soviet embassy to Dublin. To gain insights from a wider societal perspective with oral and private archival evidence, an account of the Ireland-U.S.S.R. Society – a unique friendship organisation located at a conjunction of informational, cultural, academic, trade union and tourist affairs in Irish- Soviet relations – is next presented. The final two areas of study draw upon archival records of the Irish Department of Foreign Affairs for the years 1974-80, which have only recently been made available at the National Archives of Ireland. Drawing in the main on the central registry series of files containing political reports sent to Dublin by Ireland’s first ambassador to Moscow, Dr Edward Brennan, the penultimate focus is upon the ‘island of Ireland’ elements of those reports. Lastly, the thesis discusses Ireland’s second relationship with the Soviet Union, as mediated through European Political Cooperation (E.P.C.), a parallel framework of the European Economic Community. This discussion is principally facilitated by the records of Ireland’s involvement in a confidential subgroup of E.P.C. – the Eastern Europe Working Group – which was dedicated to an ongoing compilation of studies of the Soviet Union and its fellow member states of COMECON.