Quantitative models of carcinogenesis that are based on stochastic proliferation of cell types have been suggested by several researchers. For the most part, these models exist only as equations in articles, or as specialized and non-portable software implementations. The consequence of this is that the models are not accessible to a broad audience of biologists who are impeded by the rigorous mathematics of the theoretical treatment or awkwardness or unavailability of software. The investigator's propose to develop easy-to-use microcomputer software in which the variety of important models of carcinogenesis are implemented in a generalized package. From this platform researchers will be able to explore the consequences of the various assumptions made by the disparate models, as well as construct new models from the building blocks of basic assumptions about cell proliferation, cell type transformation, and other important factors. Empirical toxicologists who possess data will also be able to use the software to estimate risk or probability of cancer under any of the competing models.