Plasma‐resonance light scattering has been observed from alkali metal particles condensed from atoms in a flowing inert gas. Lithium, sodium, potassium, rubidium, and cesium vapors were found to spontaneously form particles from 0.5 to more than 200 Torr inert gas pressure. Wavelengths of observed resonances agree with those calculated for spherical particles of 5–50 nm diameter. Using the resonance peak position as an indication of particle size, it has been possible to study the growth of the particlesin situ. . Particle size was found to be a function of the metal, metal vapor pressure, inert gas, inert gas flow rate, and total pressure, with prime factors being the transit time from the furnace to the observation region and metal vapor concentration.