In this paper we discuss light scattering experiments on random media consisting of dielectric particles (TiO₂, polystyrene) in a medium (air, water) having another refractive index. A rigorous scalar wave theory is treated as a model to represent the enhanced backscattering (weak localization) of light for finite slabs, and a diffusion approximation to this theory is discussed. Experiments and theories are compared, and effects which are the consequence of the vector character of light are explained. We comment in some detail upon the backscattering-enhancement factor. On the basis of experimental results we speculate about the possibility to observe strong localization of light.