This paper, drawing on a study of contemporary forms of disciplines and disciplinarity across schools and universities, argues that even when a case for the distinctive value or power of disciplines is accepted, the selection of content in school subjects cannot simply be logically derived from disciplines. Rather the social character of disciplines and also of systematic learning over time requires other kinds of considerations, including questions about who is to authorise the selection (national, local etc.). The empirical project on which the paper is based illustrates the tight link between social and epistemological issues for schooling – not just as matters of pedagogy, but as curriculum issues about knowledge and about the nature of the disciplines.