Contemporary citizenship education tends to focus on the development of skills through real experiences, which has led to a relative neglect or simplification of knowledge and understanding. This article outlines a framework for analysing citizenship curricula drawing on Young's notion of 'powerful knowledge' and 'knowledge of the powerful' and on Shulman's account of subject knowledge, which includes substantive concepts and epistemic criteria. These ideas are used to analyse the citizenship curricula in the four nations of the UK and Ireland to assess the extent to which they provide an adequate account of knowledge and understanding of citizenship. The article concludes that it is important to reconsider the relationship between the genuinely educational aspects of citizenship education (where 'powerful knowledge' opens up new and diverse understandings) from the normative aims, which are more akin to a form of socialisation (where 'knowledge of the powerful' closes down certain possibilities).