): The Aspen Cancer Conference, a series of yearly meetings, emphasizes the relationships between toxicity, cell injury, and carcinogenesis. The purpose of these meetings was, and continues to be, to assemble a group of leading scientists working in a wide range of disciplines and representing industry, government, and academia to confer formally and informally on current concepts and aspects of research which transcend the normal boundaries. During recent years, the emphasis has focused increasingly on the molecular aspects of toxicity and carcinogenesis and on the relationship between the two as they relate to human risk. The format consists of invited presentations and discussions in the mornings and poster sessions and informal discussions in the afternoons and evenings, fostered by the environment provided in Aspen, Colorado. One of our goals is to sponsor attendance to post-doctoral fellows, graduate students, medical students, and veterinary students, with special efforts being made to guarantee diversity. We have encouraged the participation of young investigators for the last several conferences and include poster sessions through which informal contact in mutual areas of interest can be made with established investigators. This, along with sessions in the applications of new technology in related areas of research, should assist greatly in future developments in these fields. The 1997 Aspen Cancer Conference: Mechanisms of Toxicity and Carcinogenesis will consider mechanisms of toxicity, growth control, and differentiation, as well as strategies for toxicity and carcinogenesis testing and innovative approaches to cancer chemotherapy, specifically DNA repair-mismatch, cell death, signal transduction/translational research, status of molecular diagnosis, carcinogen assessment strategy, mechanistic paradigms in risk assessment, tumor progression, cancer therapy, and stem cells.