Cambodia has been ranked as the country second most affected by extreme weather events in 2011. Between November 2011 and October 2012, government staff from different countries came together at a course facilitated by the International Institute for Environment and Development to share and reflect on their countries’ experience and needs around integrating climate change into development planning. Based on these discussions, they identified three building blocks for successful mainstreaming: an enabling environment, policies and planning, and projects and programmes. This paper reflects on Cambodia’s experience against this building blocks framework. It identifies entry points for mainstreaming climate change into sub-national planning scales, including the Strategic Framework for Decentralisation and De-concentration under the National Programme for Sub-National Democratic Development, and the development of a guideline for mainstreaming climate change into sub-national planning.