Unusually, perhaps, for a discussion of the political economy of policy reform, it begins with a look at the role of evidence and analysis - reflecting the fact that much of the pressure for environmental policy reform arises not from the complaints of agents currently suffering the consequences of the status quo, but from forward-looking scientific analyses of the impact of human activities over a long time horizon. This is followed by a relatively simple sketch of other influences on behaviour and the policy process and a look at environmental policy processes. Five cases of environmental policy reform are then analysed in some detail in order to assess the impact of some of the factors that appear to explain the success, or failure, of environmental policy reforms.