This is a wide-ranging analysis of the internal dynamics of Irish republicanism between the outbreak of ‘the Troubles’ in 1969 and the Good Friday Agreement of 1998. Engaging a vast array of hitherto unused primary sources alongside original and re-used oral history interviews, ‘The Age-Old Struggle’ draws upon the words and writings of more than 250 Irish republicans. This book scrutinises the movement's historical and contemporary complexity, the variety of influences within Irish republicanism, and divergent republican responses at pivotal moments in the conflict. Yet it also assesses the centripetal forces which connected republican organisations through decades of struggle. Across five thematic chapters, ‘The Age-Old Struggle’ offers new insights into republicanism’s multi-layered interactions with the global ’68, tactical and strategic change, revolutionary socialism, feminism, and religion. Drawing on political periodicals, ephemera, and interviews with activists throughout the ranks of several republican groups, the book roots its analysis in republicanism’s temporal and spatial complexity. It contends that the cultural significance of place, interactions with class and revolutionary politics, and shifting intra-movement networks are essential to understanding the movement’s dynamics since 1969.