Capillary electrophoresis (CE) can be used to determine the electrophoretic mobilities of polystyrene particles from the migration times of these particles assuming that (1) the particles do not interact with the capillary wall, (2) the particles can be detected, and (3) the colloidal suspension of particles is physically stable over the time course of the CE experiment (i.e., > 5 min). CE offers advantages of small sample size, automation, and ease of analysis. CE determined mobility data are used to qualitatively assess the adsorption of polymeric surfactants onto polystyrene particles.