In the stability analysis of earth slopes the simple computational methods, referred to the classical limit equilibrium approach, are not able to predict complex processes as progressive failure. Such a phenomenon can be studied only using procedures that are able to simulate the formation and development of a shear band in which plastic strains localise. From a computational point of view, this presents many problems, because the numerical analyses, carried out with local elasto-plastic models, are affected by a lack of convergence and the solution depends strongly on the mesh adopted. For this purpose, a non-local elasto-viscoplastic model, implemented in the finite element code TOCHNOG, is proposed in this book. In order to assess the validation of the model, two ideal examples are analysed: a plane strain compression test and a stability analysis of a slope with a given groundwater level. The proposed approach allows to overcome the problems of the local elasto-plastic models and, therefore, it can represent an useful analysis tool of progressive failure for the geotechnical engineers.