The Human Genome Project has made available a massive database of information on the blueprint of human life. A flood of data in the various fields of biology has led to a systems approach whose goal is to integrate biology, mathematics, and engineering in its efforts to understand and utilize the massive amounts of “information on genes, proteins, cellular dynamics, and organisms’ responses to … the environment” [1]. A deluge of information is also being collected in fields such as physics, meteorology, economics and a host of other disciplines. The next step is to integrate this data into models and simulations that will allow us to explore, understand, and make predictions at the systems level. Object Oriented Simulation [OOS] is the natural approach to utilize this data to both model and build simulations at the systems level. It is an approach that is equally applicable to the diverse fields of biology including neuroscience, epidemiology, and forestry; and also to the field of economics such as the study of market behavior. But what is OOS?