Regardless of what meaning a user attaches to fire-danger ratings the expected fire behavior is the common base on which any interpretation ultimately depends. In order for a fire-danger rating system to be useful, it must accurately and consistently predict the basic aspects of fire behavior, rate-of-spread and intensity. Of the principal elements of the fire environment, fuels have been one of the most difficult to relate quantitatively to fire behavior. With the inception of the fuel model concept a new approach to the incorporation of fuels information in fire-danger rating is being introduced. The fuel model simulates a fuel complex that represents one or more cover types which have similar fuel properties. A model consists of the fuel bed and fuel particle descriptors which are needed as inputs to equations which evaluate rate of spread and intensity. At the present time, eight models have been constructed; perhaps two more will be available by January 1972. Ultimately 25 to 30 will be needed to provide fire protection agencies with the desired resolution. © Society of American Foresters, Bethesda, MD. Abstract reproduced by permission.