Environmental and occupational epidemiology are in the tradition of "critical science." Critical science is a mode of science in which scientific methods are used to critique the adverse consequences of technological development. Critical science should be explicitly recognized as a paradigm in interdisciplinary research. It is the "mode" in which environmental and occupational epidemiology function and the role that these and related disciplines play in society. As the feedback to society on the performance of technology, critical science has assumed a major role in modern society by providing an acceptable critique of technological development. The close association between scientific research and technology of the last three and one-half centuries has been the exception to the historical rule. Intelligent guidance of technology in modern society makes public participation and education in scientific, biomedical, and technical affairs imperative. Critical science in its interdisciplinary dimension is imperative to this public process. Truly interdisciplinary work can only be accomplished when the disciplinary underpinnings are strong and when individual investigators are encouraged to pursue their individual priorities. Critical science is no exception and requires encouragement of skepticism on the part of the investigator toward conventional assumptions.