These proceedings are for the Fifth EPA Fundamental Combustion Research Contractors Workshop, held January 23-25, 1980, in Newport Beach, CA. The purpose of the workshop was to exchange information between the various contractors engaged in fundamental combustion research for EPA and to coordinate their activities. In addition, the workshop provided for a review of EPA's Fundamental Combustion Research (FCR) Program by EPA's Science Advisory Board. The workshop sessions dealt with gas-phase chemistry and heterogeneous NO reduction, chemical and physical effects of thermal decomposition, bench-scale reactor studies, two-phase turbulent flames, and model development. The main thrust of EPA's FCR program is elucidating the mechanism of NO formation from fuel-bound nitrogen. Several papers addressed the gas-phase conversion of fuel nitrogen species to NO, N2, HCN, or NH3. Advanced diagnostic techniques were used to investigate the physical changes taking place during the thermal decomposition of pulverized coal particles. Bench-scale reactor data were presented on the conversion of fuel-bound nitrogen to NO in liquid- and solid-fuel flames. Studies on turbulent diffusion flames included detailed characterization of nonswirling coal flames and methods of measuring droplet size from fuel oil atomizers.