The National Fire Danger Rating System and the Fire Behavior Prediction System were tested on prescribed fires burning uderneath canopies in six fuel types in Yosemite National Park, California. The mea error for rate of spread was +0.03 .foot per minute for the NFDRS and -0.15foot for the FBPS. For flame length factors for correcting the mean error was -0.38 .foot br both systems. Regressions provided predicted values.