Modeling is often used by researchers to evaluate innovative production systems according to their own views and agendas. Based on a whole farm spreadsheet simulation tool called CLIFS (Crop Livestock Farm Simulator) our approach aims to support farmers in reconsidering their production strategies by evaluating ex-ante a range of alternatives in line with their objectives. Initial, Project, and Alternative Scenarios are successively designed and evaluated in a face-to-face interaction with the farmer. Each scenario corresponds to a system configuration, for which CLIFS calculates staple food, forage and organic manure balances, crop and livestock productions, and economic results according to the characteristics of crops (cropping pattern, technical sequence and yield per crop), herd (size, reproductive strategy and feeding practices per batch) and prices of inputs and outputs. The approach has been tested with small samples of farmers (2 to 15) in a range of French and Tropical contexts and of production systems. Simulated projects cover topics such as increasing milk production, improving feed autonomy, adopting conservation agriculture techniques, introducing new animal units, evaluating sensitivity of farm performances to climatic and economic shocks. Farmers appreciate the closeness of the simulated scenarios with their own context, the holistic approach of their farm and the reevaluation of their projects. Next step will consist in adapting this approach to advisers' working context and using it as a training tool with groups of farmers, professionals and students.