This paper deals with an empirical study, which aims at showing the effects of the integration of modelling tasks into daily school routine in a comprehensive manner. At first the theoretical and methodological approach is explained. The main part of the paper deals with the results of the study. On the one hand the results show obstacles to the incorporation of modelling into everyday teaching practice and on the other hand the opportunities offered by this incorporation. [Paper presented at the Annual International Congress on Mathematical Education (10th, Copenhagen, July 2004).]