The Fourth International Workshop on "In Vitro Effects of Mineral Dusts on Cells" was held on September 20 - 23, 1988 in Auberge Estrimont, Orford, Quebec, Canada. The emphasis of the N. A. T. O. Advanced Research Workshop was the use of cell and organ culture and lavage cell populations obtained from man and laboratory animals to elucidate cellular and molecular events occur­ ring after their interaction with fibrous and nonfibrous particulates, including metal compounds. In seven sessions, an international representation of scientists from 17 countries (Austria, Belgium, Canada, France, Federal Republic of Germany, India, Japan, Netherlands, Norway, Poland, Portugal, Union of South Africa, Sweden, Switzerland, United Kingdom, United States of America, and Yugoslavia) presented recent research findings in the following areas: Epithelial cell injury and proliferation by minerals. Physico-chemical properties of minerals in relation to their biologic effects. Mechanisms of dust-induced pneumoconioses. Clinical and experimental studies. Mechanisms of cytotoxicity, mutagenicity and carcinogenicity. Oxidants, cytotoxicity and disease. Mechanisms of mineral-induced inflammation. Mechanisms of carcinogenesis. A session on "Questions, risk and public policy" provided a lively discussion on the relevance of in vitro experiments to carcinogenicity studies in man and their implications in the formation of regulatory policies. VI The organizing committee for this workshop was: Co-Chairs: B. T. Mossman (USA) and R. Begin (Canada) E. G. Beck (FRG) A. Lange (Poland) A. Brody (USA) P. Nettesheim (USA) R. C. Brown (UK) Q. Rahman (India) J. Bignon (France) K. Robock (FRG) Fisher G.