Ethnonational movements have proliferated throughout the world since the American and French Revolutions first gave birth to the consciousness that every nation has a right to self-determination. Whether these ethnic-based nationalist movements are a new phenomenon which is rooted in the Industrial Era of Europe, or are just a recent stage in an ethnic struggle that began during the initial cultural contact between two ethnically different groups and has persisted ever since, determines the point at which an analyst will choose to begin his or her investigation. Ultimately, the selection of this starting point determines the conclusions drawn about the cause and nature of ethnonational movements. In this thesis, the exploration of Irish ethnonationalism begins in the twelfth century when the Anglo-Normans invaded Ireland. The formation and development of the Irish ethnic group is analyzed, and self-identification found to be the key criterion for determining group membership. As social cleavages between the "Irish" and "colonizer" hardened, institutions and structures emerged to maintain and reinforce the ethnic boundary between these two groups. The thesis concludes with a detailed analysis of the operation of one mechanism of self-segregation--separate education—using ethnographic data and autobiographical accounts of the childhood experiences of people who were born and raised in Northern Ireland. In this thesis, it is argued that Irish ethnic consciousness was brought into awareness when the invading Anglo-Normans threatened to dissolve into chaos the existing Gaelic social order. It is contended that the ethnic struggle in Ireland which began in the twelfth century and still persists today in Northern Ireland, has no single cause, but was and still is fundamentally a cultural conflict which continues to be fuelled by a long history of "remembered" grievances—cultural, political, and economic--most of which predate industrialization and the American and French Revolutions. This past is kept alive by the institutions, structures, and practices which maintain and reinforce the ethnic boundary between Catholics and Protestants in contemporary Northern Ireland, thus ensuring that the Irish nationalist movement will continue to have at its disposal a sharply defined ethnic group which it can mobilize when necessary, and from which it can recruit new members. / Arts, Faculty of / Anthropology, Department of / Graduate