The report gives results of a study in which NOx emissions and general combustion performance characteristics of four burners were evaluated under experimental furnace conditions. Of primary interest was the performance of a low-NOx Distributed Mixing burner (DMB), which was tested in a nominal full-scale (120 million Btu/hr or 35MW) version and in a corresponding half-scale version. Performance was compared against a half-scale commercial low-NOx Dual Register burner (DRB) and a 120 million Btu/hr commercial Circular burner. The report documents the performance of each burner type over a wide range of firing conditions and for different bituminous and subbituminous coals. Additional test program goals were to provide information relating to the effects of burner design, burner scale, and thermal environment on NOx emission performance. Full- and half-scale DMB performance was compared under equivalent thermal conditions; the DMB was tested under two levels of furnace insulation; results from the DRB and Circular burner were compared to field data from two utility boilers operating with corresponding burner designs and coal types. A burner zone heat liberation rate parameter was used to compare the relative performance of the different burners under the various firing conditions.