This paper presents development and evaluation of a personal sampler for particulate matter that allows separation of airborne particles by size. The Personal Cascade Impactor Sampler (PCIS) is a miniaturized cascade impactor, consisting of four impaction stages, followed by an after-filter. Particles are separated in the following aerodynamic particle diameter ranges: < 0.25, 0.25-0.5, 0.5-1.0, 1.0-2.5 and 2.5-10 μm. The PCIS operates at a flow rate of 9 LPM using a very high efficiency, battery-operated light pump at a pressure drop of 11 in H2O (2.7 kPa). PTFE (Teflon), quartz and aluminum substrates were chosen for characterization of the PCIS. Laboratory tests conducted with monodisperse polystyrene latex (PSL) particles as well as polydisperse ammonium sulfate and ammonium nitrate aerosols corroborated the cutpoints. Our experimental characterization identified 2.5 cm Teflon filters as ideal impaction substrates because they result in high collection efficiency of particles above the cutpoint of each stage without the use of adhesive coatings, do not collect excessively particles below the cutpoint (a problem encountered with the use of quartz substrates) and because of their ability to be used for gravimetric analysis. Particle loading tests indicated that the PCIS stages could collect up to 3.16 and 0.7 mg of fine and coarse PM, respectively, without any loss in the collection efficiency, which would have been a result of particle bounce. (C) 2002 Elsevier Science Ltd. All rights reserved.