Fuel and vegetation spatial data layers required by the spatially explicit fire growth model FARSITE were developed for all lands in and around the Selway-Bitterroot Wilderness Area in Idaho and Montana. Satellite imagery and terrain modeling were used to create the three base vegetation spatial data layers of potential vegetation, cover type, and structural stage. Fire behavior fuel models and crown characteristics were assigned to combinations of base layer categories on these maps by local fire managers, ecologists, and existing data. FARSITE fuels maps are used to simulate growth of prescribed natural fires in the wilderness area, aiding managers in the planning and allocation of resources. An extensive accuracy assessment of all maps indicated fuels layers are about 60 percent accurate. This methodology was designed to be replicated for other areas.