The authors discuss the relaxation, reconstruction and dynamics of both (001) surfaces of SrTiO₃ (SrO and TiO₂ surfaces) in the framework of shell models. The treatment of the SrO surface (surface I) on the basis of a bulk shell model leads to relaxation- and surface-dynamical results, the former of which are in good agreement with recent LEED measurements. However, for the TiO₂ surface (surface II), surface-related changes in the Ti-O short-range interactions have to be introduced in the model in order to obtain agreement with the LEED results, as well as to assure dynamical stability of this surface. Both surfaces exhibit soft-mode behaviour which, upon lowering the temperature, leads to surface reconstruction that takes place prior to the antiferrodistortive transition of the bulk.