The calms processor (CALMPRO) is a computer program that eliminates the influence of calms on pollutant concentrations calculated by air quality dispersion models. The procedure disregards concentrations for hours when the winds are calm. The hour is treated as missing and a convention for handling missing hours is employed. CALMPRO produces statistics on the occurrence of calms in the meteorological data set and recalculates average concentrations for 1-hour, 3-hour, 8-hour, 24-hour, and annual time intervals. Technical details on the processor are presented with complete descriptions of data requirements and output. An example application of CALMPRO and the source program listing are included as appendices.