Farm land expansion in former forest areas and conservation of head watersheds is a very controversial issue in northern Thailand highlands. In the last 3 decades, tremendous change occurred in these very heterogeneous and variable montane agrarian systems, leading to new farming practices, an increased diversity of farm types, but also new relationships with national environmental policies and global conventions. The livelihoods of marginal ethnic minority farmers who cultivate the sloping highlands will remain socially and economically vulnerable if they do not decrease the risk of land degradation. Following many failed projects aiming at introducing external soil erosion control techniques, the true participation of farmers is crucial for the on-farm agronomist aiming at improving local land management. Innovative approaches, conceptual and practical tools for systems agronomists emerged in the last decade to better interact with farmers in a dynamic and integrative way. Collaborative modelling can be used to facilitate dialogue among types of stakeholders (including researchers), to share knowledge and different perceptions about land and crop management issues, and to provide adapted mediation support tools for collective decision and action. But how to share research results with producers and extension workers in an appropriate way in the above-mentioned context? What kind of models could facilitate such exchanges and be really used to support farmers' individual and collective decision-making?