The ongoing development of sophisticated fire behavior, fire effects, and carbon balance models and the implementation of large landscape assessments has demonstrated the need for a comprehensive system of fuelbed classification that more accurately captures the structural complexity and geographical diversity of fuelbeds. The Fire and Environmental Research Applications team (FERA) of the Pacific Northwest Research Station, U.S Department of Agriculture, Forest Service, is developing a National System of Fuel Characteristic Classification (FCC) to accommodate this need. The system will provide consistently organized fuels data along with numerical inputs to fire behavior, fire effects, and dynamic vegetation models. Users can generate fuel characteristics by accessing existing fuelbed descriptions (fuelbed prototypes) using generic information such as ecoregion, cover type, or vegetation form. Fuelbed default settings can be enhanced using more detailed information about vegetation structure and fuel biomass. When the user has completed editing the fuelbed data, the FCC system calculates or infers quantitative fuel characteristics (physical, chemical, and structural properties) and probable fire parameters. The system will assign the selected or enhanced fuelbed a fire behavior fuel model and a FCC potential number that describes the fuel complex based on fire behavior, crown fire, and available fuel potentials. These assignments will facilitate communication among users. The FCC software system is supported by a large data library that warehouses fuels information including biomass equations, physiognomic features, and physical parameters. This information was compiled from published and unpublished literature, photo series datasets, and expert opinion from across the United States. The system will be housed on the worldwide web and be available for use in late 2003.