Ethnically divided societies that might be described as 'balanced bicommunal' (where there are two communities, each of which comes close to representing half of the population) pose a particular challenge to conventional principles of collective decision-making, and commonly threaten political stability. This article analyses the experience of two such societies - Northern Ireland and Fiji - with a view to exploring whether there are common processes in the route by which political stability has been pursued. We assess the manner in which a distinctive relationship with Great Britain and its political culture has interacted with local conditions to produce a highly competitive, bipolar party system. This leads to consideration of the devices that have been adopted in an effort to bridge the gap between the communities: the Fiji constitution as amended in 1997, and Northern Ireland's Good Friday Agreement of 1998. We focus, in particular, on the use of unusual (preferential voting) formulas for the election of parliamentarians and of an inclusive principle in the selection of ministers, and consider the contribution of these institutional devices to the attainment of political stability. We find that, in both cases, the intervention of forces from outside the political system had a decisive impact, though in very different ways. In addition to being underpinned by solid institutional design, for political settlements to work effectively, some minimal level of trust between rival elites is required.