At an abstract level, biodiversity policies are about change. Successful policies change the way society interacts with the natural environment so that society gains most from the use and/or conservation of biologically diverse habitats and ecosystems. These potential welfare gains from changes in the use of habitats and ecosystems are the foundation for, and deliver political legitimacy to, specific biodiversity-related policy objectives. The starting point for such biodiversity policies is the realisation by policy-makers that such welfare gains can be achieved. Policy objectives then must state the outcomes to be accomplished. Typical examples of such objectives are “the preservation of a genetically viable population of Maculinea in its natural habitat up to the year 2100” or “a reduction of pesticide exposure of songbirds in the UK by 10% by 2010”.