Using the Hartree-Fock single-excitation configuration interaction (CI) model, the second- order nonlinear optical dielectric tensor, refractive index, reflectivity, circular dichroism (CD), birefringence coefficient (θ) and the effects of spatial dispersion of the simple cubic (sc) phase of the La@C82 crystal are calculated. It is shown that the intermolecular polarization interaction has significant effects on the nonlinear properties of the endohedral fullerenes, and that, in some contrast to other organic species, nondipolar contributions to this interaction are important. The spectral shapes of the second-order nonlinear dielectric tensor of the La@C82 crystal turn out to be determined mainly by the geometrical distributions of the pentagons in the fullerene structures. Our results on the effect of spatial dispersion show that the nonlinear refractive index and reflectivity of the La@C82 crystal in the energy range 0.3–6 eV have sharp structures in each band.