Climate change is a growing challenge facing the entire world. Today, most actions are aimed at mitigation. However, some climate change impacts will be unavoidable. This explains a growing interest in adaptation to climate change. On a political level, adaptation is a challenging concept. At this level, there is a growing literature on “climate policy integration” theory (stemming from the environmental policy integration paradigm). It proposes to take climate change into account in each and every sectoral policy. This contribution addresses the way to integrate climate change adaptation into policies. We will focus on regional and external adaptation strategies, from a theoretical and practical perspective. First, we will present the concept of adaptation, as a political challenge. The “climate policy integration” theory will be defined and its practical application, which has links with both vertical and horizontal integration of adaptation, will be explained. A second part of our paper will address the practical implementation of climate change adaptation at two policy levels. We will first analyse regional adaptation strategies and plans of several European countries, with regards to integration of adaptation in different sectors. These policy instruments will be analysed, as well as the perception of adaptation by various concerned actors at the regional level. Secondly, the focus will be on how adaptation to climate change can be integrated into external policies. This will be studied through development aid. Two different approaches will be described. Institutions such as the E.U. or the World Bank often highlight the need to take climate change into account while working on any development projects. This is the so-called mainstreaming approach. On the contrary, a sectoral approach of adaptation, such as proposed by NAPAs , will be aimed at reducing the vulnerability of a specific sector. Both approaches will be analysed, through scientific and official literature.