The Mekong River Commission (MRC) was established in 1995 between the governments of Cambodia, Laos, Thailand and Vietnam. The MRC Mission is: “To promote and coordinate sustainable management and development of water and related resources for the countries’ mutual benefit and the people’s well-being by implementing strategic programmes and activities and providing scientific information and policy advice”. The MRC’s Climate Change and Adaptation Initiative (CCAI) started in August 2009 as a regional collaborative initiative to support Lower Mekong Basin (LMB) countries in adapting to the impacts and new challenges of climate change. The CCAI focuses on: (i) climate change impact and vulnerability assessment, adaptation planning and implementation in priority locations within the LMB; (ii) building knowledge and capacity at different levels (institutional, technical and managerial capacity); (iii) regional adaptation strategy supporting national frameworks; (iv) regional partnership and collaboration. This presentation will focus on the recent climate change impact assessment and adaptation planning work that MRC CCAI have undertaken. In particular, the criteria and methodology used to develop climate change scenarios, along with quantifying and accouting for the associated uncertainties, will be summarised. The paradigm shift, that MRC has adopted, towards a decision led (bottom-up) approach to climate change adaptation that decouples the impact and vulnerability assessment from the climate model based scenario development will also be discussed. Adaptive water resource management such as this is occuring internationally and lessons can be learned from the MRC approach that would be applicable and useful in the Australian context (e.g. the Murray-Darling Basin).