Climate change adaptation is an area of growing concern and engagement for many developing countries. The myriad and uncertain effects of a changing climate pose significant risks for development and achievement of the Millennium Development Goals. Numerous initiatives and financing mechanisms aimed at assisting countries with climate change adaptation have been rolled out and are being implemented. Efforts also concentrate on developing specific adaptation measures, with a focus on the ones that correspond to countries most urgent and immediate needs. Increasingly, countries are coming to realize that, in the long term, climate change adaptation needs to be supported by an integrated, cross-cutting policy approach. The purpose of this guide is to provide practical, step-by-step guidance on how governments and other national actors can mainstream climate change adaptation into national development planning as part of broader mainstreaming efforts. The guide draws on substantial experience and lessons learned by the UNDP-UNEP Poverty- Environment Initiative in working with governments to integrate environmental management for pro-poor economic growth and development into national development planning and decision-making.