Climate change and it's societal response in the form of mitigation and adaptation strategies have potentially very large impacts in different sectors, especially on regions with a high vulnerability. Climate change will greatly affect agricultural and natural ecosystems and urban centers. The scale and complexity of the interactions represent a challenge for policy makers, researchers and the public at large. It is the role of the policy maker at different levels of government to facilitate and encourage adaptation and to achieve the level of transparency needed to obtain the public support for taking far-reaching measures. The European Climate Adaptation Platform Climate-ADAPT supports Europe in adapting to climate change by providing information and knowledge on expected climate change, current and future vulnerability of regions and sectors; letting users learn from each other's national and transnational adaptation strategies, adaptation case studies and potential adaptation options and, guidance on how to plan for adaptation. The platform was developed through an intensive collaboration with stakeholders, climate adaptation experts, a steering committee and the donor in 1.5 years. Different groups provided feedback at different time intervals ranging from biweekly teleconferences to quarterly workshops. The close collaboration promoted buy-in, an ongoing commitment of users and donors and several champions promoting the platform. In the first three months of the project a scoping document and a software concept were created using semi-structured interviews and wire-frames. During the development phase evolutionary prototypes were used to elicit feedback in the form of comments, paper sketches and story boards to be i mplemented in the following increment. In this process insights changed, new tools were conceived and some early ideas were dropped.</p