Overprotection from natural surface fires in the mixed conifer forest of Yosemite National Park has caused unnatural vegetation changes and increased fire hazards. Fire is being reintroduced as a management tool to rectify these conditions. This report presents results of a study on the effects of prescribed fires burning in four fuel types and over a range of weather conditions on fuel, fire, and vegetation characteristics. Fuel moisture level, fuel type, and direction of burning were found to have significant effects on fire characteristics, fuel reduction, and vegetative composition. Information gained from the study was used to refine burning prescriptions. The application of the results of this study will allow the resource manager to simulate natural fires with prescribed fires and to plan and implement burning programs.