For environmental legislation to 'work' it must not only be well designed but also efficiently and effectively enforced. Strategies must be developed as to how inspectors should go about the task of intervening in the affairs of regulated organisations to ensure compliance and enforcement-a question regarding which there is little consensus. This article examines this question from a number of angles: descriptive; analytical; and normative. It explores the practices of a representative sample of environmental regulators, identifying a number of distinctive intervention strategies (which are only limitedly shaped by existing theoretical models). It goes on to examine the strengths and weaknesses of each strategy and to consider how best to balance the sometimes competing criteria of effectiveness, efficiency and legitimacy. Finally, it considers how resource allocation and intervention strategies can best be integrated, whether there is a single 'best practice' strategy, and if not, what sorts of hybrids might be developed.