The sustainable management of renewable resources is often complicated by the diversity and dynamic nature of the ecological and socio-economic systems involved. As the dynamics and interactions of these systems are highly complex and frequently unpredictable, there is a need to opt for transdisciplinary research addressing adaptive and integrated management of renewable resources. Companion modelling (ComMod) is a multi-agent systems (MAS)-based approach relying on synergistic effects between role-playing games (RPG) and agent-based models (ABM) to facilitate collective information sharing and learning, and to improve coordination among stakeholders for negotiation and decision-making. The iterative and adaptive sequences of fieldwork with modelling activities allows the mutual and interactive participation of stakeholders during the design, implementation, calibration and validation steps of the models, as well as exploration of possible scenarios. ComMod was implemented in a study of the conflict between two ethnic communities and a newly proposed national park in Northern Thailand. Deforestation, biodiversity conservation and the livelihoods of the villagers were key issues discussed during RPG sessions with small groups of participants, and subsequently represented in an ABM simulator used with a larger audience. Consequently, the local stakeholders learned about agro-ecological and socio-economic dynamics and gained an increased awareness of these key issues. Mutual understanding was improved, and the importance of collaborative discussion, essential to negotiations and decision-making, became obvious. Finally, this Northern Thailand experience has shown that collaborative interactions mediated by ComMod were supportive of improved communication and joint learning for the adaptive and integrated sustainable management of renewable resources.