In the process of state formation, representative institutions often serve as a primary arena in which authority is ‘negotiated’ between princes and subjects—or, in the case of colonial legislatures, between the agents of metropolitan governments and settler elites. The medieval Irish parliament falls into the latter category. It was an assembly of English colonists in Ireland presided over by a chief governor, who held the place of the king of England. The present essay investigates the process of ‘negotiation’ in the Irish parliament between c.1370 and 1420. It shows how parliament served both as a source of legitimation for unpopular chief governors and, conversely, as a forum for expressing the grievances of the settler community. The essay explores the complex structure of colonial politics by locating parliament within a matrix of institutions linking Ireland to England; and, in the final section, the discussion moves into the world of political ideas. The underlying issue that it seeks to address is how ‘parliamentarianism’ helped to shape the political identity of the colony. Expressions of dissent in parliament drew heavily upon English political traditions. To that extent Irish parliamentary disputes reinforced the Englishness of the colony's political culture; but, in a paradox familiar from later colonial situations, the rhetoric of English liberty was frequently turned against the crown's own representatives. Thus it is argued that the conflicts played out in the medieval Irish parliament acted as a catalyst in the crystallization of a distinctively colonial identity among the English of Ireland.