A computer-based economic model of arable, forestry and silvo-arable systems has been developed as part of the ‘Silvoarable Agroforestry for Europe’ project. The process of developing the model Farm-SAFE is described in terms of: the model background and purpose, the systems modelled, the objective of the economic analysis, the viewpoint of the analysis, the spatial and temporal scales, the generation and use of biophysical data using LER approach, and the inputs and outputs. The objectives of the economic analysis are to compare silvo-arable, arable and forestry systems at a one-hectare/plot scale, and to determine the feasibility of silvo-arable systems at a farm scale. But the main problem of this model was that it was running on a spreadsheet. The lack of user-friendliness or public interface and the difficulty of testing several scenarios (memory space, saving scenarios and data management) was preventing its future use for common users, farmers or technicians. During the last 2 years, the process of development was initiated in France inside the “National Development Program – Agroforestry 2006/08”. The main decision was to propose a free version, accessible to any users connected to the web (pHp language). A first free version of Farm-SAFE is now available (in French), constituting the first free and evolutionary software with the objective of being a planning decision-support system in agroforestry. From this software, a new program will be planned with different partners (agronomics high schools) to develop some virtual education programmes in agroforestry