This study deals with the representation of the atmospheric boundary layer within an atmospheric model of intermediate complexity, ECBilt. Such models bridge the gap between very simple low-dimensional models and full general circulation models. For example ocean modelers use them as an alternative to mixed boundary conditions. Also, climate impact researches use them to assess the impact of different scenarios. Their main advantage is the relatively short computation time. As such, many perturbed runs can be performed, making them highly suitable for Monte-Carlo climate simulations. The proposed module for the atmospheric boundary layer, describes the major processes in the atmospheric boundary layer. It includes the growth of the convective boundary layer due to increased thermal-forced turbulence, the additional heating of the unstable boundary layer through entrainment, the collapse of the boundary layer during the afternoon transition and the development of the stable boundary layer. For different sites and meteorological conditions results of the model are compared with measurements and with output from a state-of-the-art general circulation model. It appeared that the model performance gives realistic estimates for the surface flux densities. Including the boundary layer model in the climate model ECBilt leads to improvements in the modeled surface flux densities. Moreover, inclusion of the boundary layer model, gives more realistic estimates of the surface temperature and the temperature at anemometer level.