Increasingly, development is facilitated through the provision of mitigation and compensation measures. One reason for this is to get round ever more stringent conservation laws. In this article I consider this general issue through one particular lens: the role and scope of appropriate assessment under the EU Habitats Directive (92/43/EEC). Appropriate assessment is a key part of the Directive's regime for conserving Natura 2000 sites, being the threshold for a relatively stringent public interest test and ecological compensation requirement. One particular issue is how mitigation or compensation measures should be addressed through appropriate assessment. I consider this issue, looking in particular at the only reported case which deals with this: R (Hart District Council) v Secretary of State for Communities and Local Government and others. I suggest that Hart may be seen as wrongly decided at the time, and that more recent case law casts further doubt on its correctness. Drawing on other work, I suggest how decision-makers might answer the question raised in Hart differently and the scope to do this under the Habitats Directive.