Dispersions of solid particles in aqueous solutions almost invariably bear a surface charge which is compensated by an opposite charge in the solution. An electrical double layer is formed. The surface charge can sometimes be determined by titration. In practice, the electrokinetic potential or zeta potential is usually measured. This potential is a characteristic quantity for stability, rheology, sedimentation, etc., of disperse systems. This paper addresses the question of the relation of the electrokinetic potential to the static double layer parameters. To this end the author provides a detailed account of electrokinetic shear processes. In addition, new results obtained with the aid of molecular dynamics are also presented.