The term 'sustainable development' first appeared in a significant way in the World Conservation Strategy (IUCN 1980), but the basic ideas had been discussed much earlier. 'Ecologically sustainable development' became particularly popular after the publication of Our Common Future, the Brundtland report (WCED 1987). Many agencies claim that their work is highly dependent on, or governed by, sustainable development or sustainability principles. One of the major problems with the concept of sustainability, however, is that, while many people claim to be utilising sustainability principles, there is often little evidence to confirm this. Supporting data are frequently absent, perhaps because people are uncertain about the information they should collect.