The National Environmental Policy Act of 1969 (P.L. 91-90) calls for the use of "a systematic, interdisciplinary approach which will ensure the integrated use of the natural and social sciences ... in planning and in decision making which may have an impact on man's environment." Moreover, both the Environmental Protection Agency and most state guidelines consider citizen participation an essential ingredient in the assessment of a proposed project's environmental impact. However, research on and the actual use of environmental impact statements have focused on the technical, physical, and scientific implications of proposed projects much more than on the role of human values, attitudes, and beliefs in the environmental assessment process.