The Mekong river region is facing rapid changes in land and water uses which involve unevenly distributed costs and benefits among various stakeholders, and raise the issue of the resilience of ecosystems and livelihoods in the Mekong river basin. In this region, the production of knowledge on water resource dynamics is mainly based on scientific hydraulic models which struggle to integrate ecological and social impacts of water dynamics at a river basin scale. Our work aims at taking into account a diversity of viewpoints and knowledge sources on water dynamics and their impacts, in order to promote dialogue among stakeholders. In this paper we propose a conceptual framework and a methodology to promote resilient water management, and present the first results of our work in the Nam Theun – Nam Kading (NT-NKD) River Basin, a Mekong river sub-basin located in Lao People's Democratic Republic. Key basin stakeholders from the public and private sectors at multiple levels were brought together, including those from the hydropower industry, research and administration, as well as local government and villagers, into discussion arenas initiated through a participatory modelling process, called Companion Modelling (ComMod). In ComMod, participatory role-playing games (RPGs) associated with agent-based models (ABMs) are used within an iterative and evolving participatory process where stakeholders are involved in the co-construction of the common representation of the issue context and the co-design of the corresponding simulation tools. In the NT-NKD basin, the most pressing issue identified by stakeholders, and subsequently modelled, was river flood risk. The ComMod approach was implemented primarily through interactive field workshops. During these workshops, stakeholders were asked to co-design and use together a sub-basin model in the form of a RPG for land and water uses management, which includes up- and downstream interests and needs, multiple uses/managements and