Photo-induced charge redistribution is used to model the efficient second-harmonic generation of light in optical glass fibers. In this theory, second-harmonic light redistributes charge through a hopping process, giving rise to an electric field that follows the gradient of the transverse distribution of light intensity. The electric field, in conjunction with the third-order nonlinear susceptibility of the material, induces an effective χ(2). The theory predicts that the fundamental wave cannot directly convert into a second-harmonic mode that has inversion symmetry about the transverse dimensions of the fiber, it may only convert directly to an antisymmetric mode. A self-consistent treatment reveals that a single mode of the second-harmonic cannot self phase-match and therefore cannot grow in intensity to the levels experimentally observed. The presence of two modes can, however, self-consistently give rise to the growth of one of them via a spatial parametric process caused by the nonlinear nature of the charge redistribution mechanism. An intense second-harmonic field having either even or odd symmetry can ultimately arise through this modal nonlinear interaction. Apparently, however, the static electric fields predicted by the hopping model are insufficient to account for the upper range of the experimentally observed effective χ(2)'s.