A method for testing the effectiveness of fire-retardant chemicals on woody fuels has been developed. The test involves the use of a preconstructed wood crib, one-half of which is treated with a fire retardant. The speed with flames pass through the treated portion of the crib is plotted over the weight of dry chemical present. A regression curve is plotted for each chemical that reflects treatment effectiveness in accordance with amount of chemical present. The most effective chemical has the steepest curve. Of the chemicals tested, the best 'effectiveness' ratings belong to ammonium sulfamate, ammonium phosphates (DAP, MAP, and 11-37-0), and ammonium sulfate in that order.