Metropolitan areas have come under intense pressure to respond to federal mandates to link planning of land use, transportation and environmental quality; and from citizen concerns about managing the side effects of growth such as sprawl, congestion, housing affordability and loss of open space. The planning models used by metropolitan planning organizations are generally not designed to address these issues, creating a gap in the ability of planners to systematically assess them. UrbanSim is a new model system that was developed to respond to these emerging requirements and is now been applied in three metropolitan areas. This article describes the model system and is application to Eugene-Springfield, Oregon.