Addressing the problems of natural resources management requires an understanding of the complex interactions between human and natural systems. Modeling and computer-based simulation has been utilized increasingly as a tool to facilitate this understanding. Numerous simulations of natural systems have been developed, from global-scale general circulation models to more localized models of watersheds or fisheries. Such simulations are useful in providing resource managers with an indication of how these systems behave under different conditions. But while considerable effort has been devoted to the simulation of natural systems, the amount of effort devoted to modeling human systems, and their interaction with natural systems, has been relatively small. Recently, researchers have outlined the importance of developing a discipline devoted to the modeling and simulation of human systems. Increased efforts are now being devoted to the simulation of social phenomena (see, for example, Doran and Gilbert). The tools now exist to develop simulations that incorporate the behavior of both a natural resource and the human individuals or institutions that interact with the resource. A considerable body of work exists devoted to understanding the behavior of the institutions that people have developed to manage natural resources. Specifically, a large number of studies have been undertaken in an effort to understand how common pool resources (CPRs) have been managed in differing natural and institutional environments. Numerous field studies and laboratory experiments using human subjects have supported the evolution of a theoretical foundation for the study of resource management institutions. But while field studies and experiments have been useful tools for exploring the management of natural resources, to date little effort has been devoted to exploring the potential role of modeling and computer-based simulation for understanding the behavior of resource management institutions. This chapter seeks to combine the theoretical foundations of research on institutions for resource management, with recent advances in human systems modeling to outline a framework for modeling individual decision making in resource management environments. Starting with a brief review of social simulation and intelligent agent-based modeling formalisms, this chapter moves on to discuss models of individual decision making in the social sciences and in simulations..