Polymerization-induced phase separation was described using a phase transformation diagram in conversion vs composition coordinates;, where metastable and unstable regions were located. Phase separation through a nucleation-growth (NG) mechanism, in the metastable region of the phase diagram, was described with the usual constitutive equations. A distribution of particle sizes was generated as a function of conversion. Different possible composition profiles inside and outside the particles were predicted, leading to refractive index profiles associated with individual particles. Representative sets of particles were properly located in the scattering volume, and the Light scattering pattern of the ensemble was generated. A maximum at a wave vector q not equal 0 was present in the following cases : (a) at low concentrations of dispersed-phase particles when a depletion layer surrounded the particles and (b) at high concentrations of dispersed-phase particles due to the correlation produced by the location of individual scatterers in a constrained space. Both effects generated a maximum in the scattered intensity at q not equal 0, even for broad particle-size distributions. The position of q(max) increased with the concentration of dispersed-phase particles. For systems that do not exhibit coarsening effects, the light scattering peak will initially shift to the right and then grow in intensity at a constant value of the wave vector, when nucleation becomes negligible. Coarsening produces a shift of the scattering peak to the left, while increasing its intensity. Therefore, the presence of a maximum in the light scattering pattern should no longer be indicated as the hallmark of Spinodal demixing, as is frequently stated in the literature.