The sedimentation of slightly Brownian particles toward a flat plate in water has been measured using the optical technique of total internal reflection microscopy (TIRM). The particles used were 15, 20, and 25 mu m diameter polystyrene latex spheres and the plate was a polished BK-7 glass slide. The measurements were performed for dimensionless separation distances (gap width/sphere radius) ranging from 0.01 to 0.05, thus the mobility of the particles was greatly reduced by hydrodynamic coupling with the plate, The average sedimentation rate was found to agree closely with predictions made using the drag equations of Brenner [H. Brenner, Chem. Eng. Sci. 16, 242 (1961)] when the measured separation distances were adjusted by a constant offset which is believed to reflect the presence of asperities on the particle surface. In addition, the Brownian movements observed during sedimentation were found to be normally distributed with a mean of zero, also in agreement with theory. Thus by simply measuring the sedimentation rate, the dependence of both the particle’s mobility and diffusion coefficient on separation distance could be obtained. Although surface roughness on the particle limited the distance of closest approach, it did not affect the particle/surface hydrodynamics.