Selective noncatalytic reduction (SNCR) is a postcombustion technique for reducing NOx emissions from power generation facilities. The optimization of the SNCR system involves maximizing NOx reduction while minimizing NH3 slip. This requires optimization of both the SNCR system as well as the combustion, as their performances are interrelated. This work discusses the results of an optimization study of SNCR systems on a wood-fired boiler. This included measurements of NH3, which was measured with a tunable diode laser, as well as temperature, O-2, CO, and NOx. The results clearly showed the interrelationship between the SNCR process and combustion. Marked improvement in SNCR performance was possible on this boiler due in part to the availability of instrumentation that allowed the operators to optimize combustion and maintain these conditions once they were defined.