The purpose of this Whitehall Paper is first to provide a conceptual framework for the discussion of interoperability in the military context in simple language that is understandable outside specialist communities such as those of communications and information technology. The framework needs to have a wide enough application to embrace both the military, who should benefit from interoperability, and civilians who work in policy and resource allocation, who might contribute to enabling interoperability. This analysis is then used to expose some ways in which coalition interoperability might be enhanced. The study focuses on multinational interoperability. However, the analysis also addresses intra-national interoperability because its implications are highly relevant to the multinational problem.