Coordinated (or 'joined-up') approaches to policy making are said to be an immensely important ingredient in the effective governance of sustainable development. There are, however, few detailed empirical studies of how well different policy coordination instruments perform in relation to this task. This paper identifies the United Kingdom as a critical test of how to achieve better policy coordination because it has been regularly identified as an exemplar of best practice in international benchmarking exercises. Specifically, it examines the integration of the environment into mainstream policy making through the application of policy appraisal in the strategically important areas of energy, defence, and public spending. Overall, it finds that the UK's much vaunted approach to coordinating the governance of sustainable development has struggled to tame the forces of departmentalism. While deploying carefully packaged combinations of coordinating instruments may address some causes of non-joine-up behaviour, perfectly coherent policy making is always likely to remain tantalisingly out of reach.