The laser-induced breakdown spectroscopy technique has been extended to provide quantitative analysis of the mass and elemental composition of individual, submicrometer to micrometer-sized aerosol particles. A two-part approach was used for calibration of the overall mass concentration response, and of the characteristic plasma volume, equal to2.5×10−4cm3.Laboratory results are presented for submicrometer-sized particles containing a known concentration of magnetite. Additional data are presented for fine particulate matter measured in ambient air, including magnesium-containing particles with an average size of 313 nm. ©1998 American Institute of Physics.