Over the past few decades there has been a significant change in the public appreciation of wetlands. From the view that wetlands are wastelands of no benefit to humanity and whose loss is a positive benefit, we have moved to an era in which wetlands are amongst the jewels in the environmental crown, to be protected at almost any cost. This change in opinion is reflected in policies, legislation, regulation and administrative practice in many countries (see among others, Government of Canada 1991; Davidson and Gauthier 1993; Lynch-Stewart et al. 1993; Nakashima and Khan 1994; ANCA 1996; DLWC 1996; Environment Australia 1997). In part this greater appreciation of wetlands reflects more general concerns about the environment, but more particularly marks the assimilation into general knowledge of particular interpretations of the results of ecological studies of wetlands. One consequence of the increased awareness of wetland values has been a substantial upsurge in research activity. Nevertheless, I would argue that, while the case for wetland conservation is very strong, the development of wetland policies has often presumed that science provides a firmer foundation for decision making than either is, or can be, the case.