If approximately 80% of the public in the UK support wind energy, why is only a quarter of contracted wind power capacity actually commissioned? One common answer is that this is an example of the ‘not in my backyard’ (Nimby) syndrome: yes, wind power is a good idea as long as it is not in my backyard. However, the Nimby claim that there is an attitude–behaviour gap has been rightly criticised. This article distinguishes between two kinds of gap that might be confused, namely the ‘social gap’ – between the high public support for wind energy expressed in opinion surveys and the low success rate achieved in planning applications for wind power developments – and the ‘individual gap’, which exists when an individual person has a positive attitude to wind power in general but actively opposes a particular wind power development. Three different explanations of the social gap are distinguished, only one of which depends upon the individual gap. In the second section of the article the relevance of our three explanations for policy is considered. It is argued that the different explanations suggest different policy responses and that the success of efforts to increase wind energy capacity may depend on developing a better understanding of the relative significance of the three explanations.