Park managers need scientifically defensible data on which they base management decisions. The Vegetation Program at the Center for Urban Ecology (CUE) provides expertise on experimental designs and analysis of vegetation studies and long-term data sets within the parks of the National Capital Region (NCR). The classification and subsequent mapping of vegetation communities in NCR parks is a primary Program goal and is one of the 12 required data sets that parks must have. Under the National Park Service (NPS) Vegetation Mapping Program (VMP), the Vegetation Program at CUE has developed a time and cost efficient mapping strategy and is mapping all of the parks in the region as a single large park. A preliminary classification of 170 plant communities for the National Vegetation Classification System (NVCS) (also) was developed through the application of a Rapid Assessment Method. NCR's vegetation mapping is in cooperation with NatureServe (who developed the NVCS), the Virginia Department of Conservation and Recreation -- Natural Heritage Program, as well as the NPS VMP and Inventory and Monitoring (I&M) Program.