The accurate modelling of the mechanical behaviour of soil and rock is of great interest in geotechnical engineering. For modelling the complex behaviour of such materials a large number of advanced material models, based on different theories, have been developed in recent years. The aim of the Colloquium is to review the various existing constitutive models for soil and rock and to assess the potential and drawbacks of the different approaches for applications in numerical simulations of geotechnical problems. The colloquium will contribute to obtain a valuable basis for the selection of reliable and efficient material models for soil and rock and to intensify the interaction between experts in the fields of continuum mechanics, numerical modelling and geotechnical engineering.