A sensitivity analysis was conducted of the National Fire Management Analysis System (NFMAS) to better understand the relationship between data input and model outcomes, as reflected by changes in C+NVC and MEL program options. Five input variables were selected for sensitization: Unit Mission Costs, Average Acre Costs, Net Value Change, Production Rates, and Escaped Fire Limits. A stratified random sample of 32 national forests was selected, according to the distribution of national forests within Forest Service regions and fire frequency classes, on the basis of historical fire data. NFMAS database tables were obtained and manipulated, with each variable increased and decreased at six levels (+/-25, +/-50, and +/-100%). Results indicated that Production Rates was always the most influential variable, Unit Mission Costs was always least influential, and the influence of the other variables depends on the choice of model outcome. In general, greater sensitivity changes resulted in greater changes in model outcome, but no consistent pattern of influence could be found regarding program option.