We have developed a new instrument that combines phase analysis light scattering (PALS) with dielectric spectroscopy (DS) for characterizing the electrokinetic and dielectric properties of dilute colloidal suspensions. PALS measures the electrophoretic mobilities of colloidal particles, and DS provides frequency spectra of dielectric permittivity and conductivity. In addition to the improvements that we have made in each technique, the combined instrument realizes considerable cost savings due to shared electronic components. We have used the combined instrument to study an industrially relevant aqueous suspension of colloidal polystyrene particles containing excess anionic surfactant. The results confirm our expectation that treatment of the suspension with ion exchange resin removes much of the surfactant and profoundly alters the suspension’s electrokinetic and dielectric behavior.