This paper sets out some observations on the making, and use, of contemporary classifications of nature in the context of a simultaneous and on-going `making' of Europe. It looks in particular at two classifications, one of British vegetation communities and the other of European `biotopes' (a concept that closely relates to natural or semi-natural `habitats') - respectively, the UK National Vegetation Classification (NVC) and the EU CORINE Biotopes Classification. It investigates aspects of the relationship between these two classifications which has come about through their use in a European conservation policy. The CORINE Biotopes classification, in particular, represents a new ordering of nature in a very active sense: it is a good example of a `working archive', and is intimately tied into policy decisions at many levels in Europe. The paper addresses questions as to how contemporary classifications are being made and used, and whether certain tacit understandings and conceptual frameworks `built in' to them reflect back upon the world at a later stage. It argues that these classifications do not always simply reflect the assumptions and understandings built into them: once in the policy domain, they are not as `reversible' as that. Their categories quickly become unstable, mutating and interacting in sometimes unpredictable ways. The two classifications, through their relationship with policy, have a jointly evolving history. The continual renewal of meaning attached to classes within these classifications appears to reflect outwards rather than inwards - in chorus with the broader social and political context, rather than reflecting the condition of their making. In their evolving forms, they illustrate very well the complex nature of the dynamic between unity and diversity, centre and periphery, that lies at the heart of the European Union.