The self-shielding treatment of resonant isotopes is currently performed in most lattice codes using the Stamm’ler method on simplified one-dimensional geometries. A generalization of this procedure is proposed for self-shielding calculations over the arbitrary two- and three-dimensional geometries typical of most advanced reactor designs. Numerical results are presented for a simple two-region cylindrical cell and for a small pressurized water reactor assembly exhibiting true two-dimensional behavior. The absorption rates obtained after self-shielding are compared with exact values obtained using an elastic slowing-down calculation where each resonance is modeled individually in the resolved energy domain. It is shown that the generalized Stamm’ler method can be applied without loss of accuracy to multidimensional domains.