This thesis examines the conditions under which ethno-territorial cross-border conflicts can be resolved successfully. Ethno-territorial cross-border conflict is a type of ethnic conflict in which competing territorial and ethnic claims of distinct state and group actors occur; and this manifests itself primarily on three interrelated levels - inter-group conflict, conflict between the external minority and the institutions of its host-state, and the (territorial) conflict between host- and kin-state. An initial theoretical exploration of the subject establishes the framework of the subsequent study of individual cases, examining why the similar conflicts in Alsace, the Saarland, South Tyrol, and Northern Ireland required fundamentally different solutions. In addition to this, the condominia of Andorra and the New Hebrides are analysed, providing the basis upon which the concept of a condominium-style settlement for ethno-territorial cross- border conflicts is explored. By looking at the workings of integration, traditional consociation and consociation with permanent institutionalised kin-state involvement, secession, and condominium, the complexity of factors is studied that influence the development of ethno- territorial cross-border conflict, including inter-ethnic and intra-ethnic dimensions and the policies of the host and kin-state in relation to the conflict and each other. Thus refined, the analytical framework allows determining the conditions that must be fulfilled to provide lasting stability to a negotiated settlement. This set of stability criteria creates a paradigm that has relevance as an analytical tool beyond the case studies conducted in this thesis. It can be used to design case-specific solutions to actual ethnic conflicts and it can serve as an instrument to recognise instabilities in, and potential breakdowns of, existing settlements sufficiently early to respond to them constructively and to avoid a re-escalation of an already settled conflict.