On 22 May 1998 Northern Ireland and the Republic of Ireland held successful referenda on the so-called Good Friday Agreement that provided a proto-constitutional settlement to the violence that had plagued Ulster for almost thirty years. This article analyses the prospects for a lasting, stable settlement in Northern Ireland. Experience has shown that construction, like reform, of constitutions and constitutional frameworks in deeply divided societies is no mean task. This article draws lessons from Canada's failed Charlottetown Accord (1992) to suggest that two fatal flaws – expanding the agenda to include the demands of multiple groups, and opening the constitutional process to mass legitimisation through use of referenda – can undermine political stability and the prospect of settlement. Canada, a country that like Northern Ireland features a long string of failed constitutional settlements, provides an excellent illustration of the problems involved. As is the case in Northern Ireland, the Canadian constitutional quagmire has grown out of the imperative to reconcile the rights of an entrenched ethno-national minority with majority rule. In both countries the traditional defining cleavage is ascriptive. In both, centuries of resentment, as well as expectations raised and dashed by constitutional failure, have led to political instability. In Canada, this has meant threats to the integrity of the country itself. In Northern Ireland the consequences have been even more serious.