Introduction Impact assessment needs to be redefined. Despite two decades of evolution and a myriad of techniques, present practice appears unable to help in preventing environmental disasters such as the Exxon Valdez oil-tanker spill off Alaska, or poor resource management such as the wholesale removal of tropical rain forest in the Amazon or the demise of species such as the giant panda in China. These problems do not arise out of ignorance. They have not occurred because developments were unplanned, nor their impacts unforeseen. Rather, they are the results of a flawed conceptualization of impact assessment and its role in environmental planning and resource management.