This paper describes the development of ACCESS-I (Agro-Climatic Change and European Soil Suitability), a model that will simulate the soil water balance and crop growth, for soil map units within regions, under conditions of climate change. ACCESS-I has been developed for spatial application over large geographic areas, and so its data input requirements have been kept to a minimum. These include the use of meteorological data with monthly time-steps, and the estimation of soil hydraulic properties from simple soil survey data (particle size distribution, organic carbon content and bulk density) using pedotransfer functions. The soil water balance component of ACCESS-I considers evaporation and transpiration separately, as well as defining root front development and root density. Biomass accumulation is estimated using the concept of water use efficiency, and crop yields (for wheat, maize, sunflower and soybean) are calculated from the total biomass, using a crop dependent harvest index. The model considers the influence of atmospheric CO concentrations on crop yields through the water use efficiency. ACCESS-I also contains a sub-model to assess soil workability, a major constraint to crop production in northern latitudes. A spreadsheet validation protocol has been developed for ACCESS-I in which experimental datasets can be compared directly with simulation output files in the same format. Comparison of observed and modelled data from central England have shown ACCESS-I to be able to simulate the soil water balance and biomass accumulation to acceptable levels of accuracy.