The focus of this research is on simulation modeling and a multi-agent-based system for consumer deshopping behavior. Most recent work on deshopping analysis has been focused on case studies and theory building. This study intends to propose a decision framework and computational model of deshopping that combines consumer purchase with return behavior. A multi-agent system, together with simulation and associated functions, are created. The rich detail provided by simulation modeling can contain a hybrid marketplace as elements of the retail environments and two or multiple firms, competitors, Web sites, etc. To develop this computational framework and model, several integrative frameworks for evaluating deshopping, behavioral intention, rational choice, shop or Web site choice, opinion dynamics, return leniency are employed. The simulation and modeling allow firm responses to deshopping to be simulated over time. Return leniency modeling allows firm responses to be analyzed as well. The simulation model provides a bird’s eye view of the presence, impact, and growth of consumer deshopping behavior and its effect on return policies and customer loyalty.