The design and performance of an instrument for rapid single-particle mass spectrometry (RSMS) is described. Aerosols are sampled directly into a mass spectrometer where individual particles are detected by light scattering from a continuous laser beam. The scattered radiation from each particle triggers an excimer laser which ablates the particle in-flight. Ions produced from the particle are analyzed by time-of-flight mass spectrometry. The chemical composition of the particle is inferred from the distribution of ions in the mass spectrum. Since the chemical composition is determined approximately 1 ms after a particle enters the sampling inlet, chemical transformation by reaction, condensation, evaporation, or phase change is minimized. Since the ion formation process in RSMS is similar to that in laser microprobe mass spectrometry, RSMS exhibits similar attributes for single-particle analysis. These include detection of trace organic and inorganic species, speciation of inorganic materials, and the ability to distinguish the surface versus total volume composition of a particle. RSMS extends these capabilities to include semivolatile compounds and surface chemical reactions. Potential applications of RSMS to atmospheric aerosols are discussed including speciation of semivolatile and nonvolatile sulfur compounds, source apportionment through isotopic ratio measurements, and the detection of thin coatings on particles produced by condensation of reactive gases.