In these essays by historians on aspects of republicanism in Ireland (north and south) from the early 20th century to the present, a number of central themes emerge. During the course of the 20th century, republican organizations have been repeatedly faced by similar arguments, rhetoric and choices. Should they participate in political institutions which are seen to be illegitimate? Should physical force be used? Splits, schism and rivalry emerge as a significant dynamic of the political culture. Republican organizations are also shown to be ideologically incoherent, opportunist and flexible, and the struggle to claim political ownership of the republican tradition is shown to be very important. Another continuing theme is the progressive language of republicanism although in practice republican politics and activities are often intolerant.