Experiments investigating the normal impact of polydisperse microspheres with surfaces have been carried out. The incident and rebound normal velocity components and particle size were measured using the phase Doppler approach. Incident normal velocities were near those required for capture by the surface. The numerical simulation approach developed by Brach and Dunn (1995, Aerosol Sci. Technol. 23, 51-71). was improved and applied to analyze the polydisperse microsphere normal impact data. This improved approach was justified through comparisons with the monodisperse microsphere normal impact data of Wall et at. (1990, Aerosol Sci. Technol. 12, 926-946) and of Dahneke(1975, J. Colloid Interface Sci. 51, 58-65).