This article builds a taxonomy of the different functions performed by the term 'harmonisation' in contemporary policy debates. Four broad functions or domains of use are identifiedpolitical, policy, process and program -within each of which there are multiple different uses. Based on this classification, the article then develops a multi-dimensional conceptual framework through which the term can be better understood and examined, its political uses identified and isolated, and harmonisation initiatives constructed, framed and analysed. The framework should prove useful for Ministers and government departments called upon to determine if, how and to what extent to harmonise regulations in a particular area; regulators called upon to administer and enforce harmonised regulatory regimes; and regulatees, practitioners and academics concerned to understand the impact of a harmonisation task.