The electrophoretic behavior of concentrated spherical colloidal particles is analyzed theoretically for all levels of scaled surface potential phi(a), taking the effect of double-layer polarization (DLP) into account. The result of numerical simulation reveals that for a very small kappa a (<0.01), kappa and a being, respectively, the reciprocal Debye length and the particle radius, or a very large kappa a (>100), using a linearized Poisson-Boltzmann equation (PBE) and neglecting the effect of DLP is reasonable; for an intermediate kappa a, appreciable deviation may result. The deviation is negative if kappa a is small, and positive if kappa a is large. The mobility against kappa a curve may have a local minimum and a local maximum If phi(a) is low, the mobility increases with the porosity of the system under consideration, and for a fixed porosity, the mobility increases with kappa a. If phi(a) is high and kappa a is small, the effect of phi(a) (i.e., solving a nonlinear PBE) on the mobility of a particle is more significant than that of double-layer polarization, and the reverse is true if kappa a is large. For an intermediate kappa a, the effect of DLP is more significant than that of phi(a) when the porosity is high, and the reverse is true if it is low,