The properties of flames supported by pyrolysis of commercially available urethane mattress foams are described. The flame shape, flame growth, some species concentrations, solid and gas phase temperatures, and mass loss are measured during a six minute period after ignition. Functional descriptions of these empirical histories of the flame radius and height, flame spread and mass loss rates are presented. Using a simple cone-cylinder model for the flame shape, measured temperatures, soot volume fraction and H2O and CO2concentrations, flame emisstvities in the homogeneous, nongray approximation are calculated. With this information the radiant heat transfer to the urethane and the surroundings is predicted. From comparison between predicted and experimental mass pyrolysis rates, convective heating of the mattress is shown to be negligible. Comparisons are also made with independent measurements of radiant flux and mass loss. Good agreement is obtained.