Abstract. This paper reports on the multi-scale modelling of an intestinal crypt cellular structure coupled with Wnt signalling. Using formal modelling techniques based on the stochastic pi-calculus, which supports ambients needed for compartments, we develop a collection of cell and molecular level models. The focus of our study is the role of Wnt in the control of cell division and differentiation. Using the BioSPI simulation platform, we analysed the model and reveal a plausible explanation for a mechanism that ensures robustness of cell fate determination.