A complete formulation, including the local details of gas absorption-emission processes, has been made for thermal radiation in a parallel plate enclosure. The temperature is permitted to vary continuously between the plates, and the emissive power of the gas may have an arbitrary dependence on temperature. Thermal conductivity effects have been omitted. Solutions of the governing integral equations have been carried out for values of the single governing parameter kL (k = absorption coefficient, L = spacing) in the range 0.1 to 2.0. Temperature distributions and heat transfer results are given. For moderate values of kL, the temperature is quite uniform across the gas.