The particle sampling characteristics of the SRRC cotton-dust sampler have been experimentally determined for the case of calm-air sampling. The tests were performed with the entire sampler enclosed in an aerosol test chamber so that the overall particle sampling characteristics of the sampler could be deter mined with the use of monodisperse liquid particles over the size range from 2.5 to 20 µm aerodynamic diameter. The 50% cut point of the SRRC sampler was found to be 12.6 pm, with the collection efficiency varying from 95% to zero as the particle size increased from 2.5 to 20 µm. The sampling characteristics of the SRRC sampler were found to be in fairly close agreement with the vertical elutriator sampler in calm air. In addition, the experimental data have been interpreted with the use of inertial impaction theory.