Summary: This paper presents the results of an experimental investigation on the response of solid particles to a zero-pressure gradient, vertical, turbulent boundary layer in air. Two different size classified glass beads, 50 and 90 \(\mu m\) dia (Re \(\approx\) 1 and 4, respectively), were independently dispersed in the air flow with a 2% mass loading. Velocities of both the contaminant particles and the seeded air flow were measured using laser Doppler anemometry. The data show that the light particle loading had no effect on either the mean flow or the turbulence properties of the air boundary layer. The measured r.m.s. velocity fluctuations of both particle sizes nearly equaled the flow turbulence intensity in the streamise direction but were strongly attenuated in the normal direction. This paper presents a model for predicting the mean particle behavior to within 2% and the particle r.m.s. velocities to within 50%.