This policy brief reflects on the role of knowledge in the adaptation to climate change. It is not meant to be prescriptive but rather to provoke critical thinking about how information is mobilized, collated and disseminated in support of adaptation. There are four key messages. First, knowledge important to adaptation can come from sources such as science and practice, as well as experience, customs and traditions. Second, knowledge-action gaps arise not only because needed knowledge is missing, but also because existing knowledge is impractical, inaccessible or otherwise goes unused. Third, narrowing of knowledge-action gaps requires active management of boundaries between knowledge holders and users. Fourth, knowledge is important, but not sufficient for action. There must also be capacity and incentives or motivation. The brief derives from the experiences of the Adaptation Knowledge Platform. It draws on issues raised at the October 2010 Adaptation Forum held in Bangkok’s United Nations Conference Centre and in an on-going series of sharing and learning seminars.