This note describes the recent development of a new technique, aerosol time-of-flight mass spectrometry, that allows for realtime analysis of single particles. We report here the first results demonstrating the utility of this technique for real-time analysis of polydisperse systems of aerosols, determining both size and composition. Future calibration studies will follow, enabling complete analysis of complex atmospheric systems, determining particle size distributions and, more importantly, the corresponding compositional variations for each particle size.