This largely conceptual thesis explores the epistemological nature of students' engagement with disciplinary knowledge, primarily in further education contexts. The disciplinary nature of students' engagement is frequently obscured by concerns relating to their engagement with educational processes. A model which distinguishes between different forms of knowledge and which places disciplinary knowledge at the centre of the educational context is proposed. This model serves as an organising idea throughout the thesis. Approaches to theorising educational knowledge, including social realist, sociocultural and situated theories of learning as well as Bernstein's work, are analysed, critiqued and in some cases adapted. A case study of the school science curriculum and scientific literacy explores the principles of recontextualisation of disciplinary knowledge and a key debate concerning the nature of 'authentic learning' is identified. It is argued that while Bernsteinian and social realist theories are useful in elaborating the role of forms of knowledge within the curriculum, these theories tend to neglect social relations to knowledge in different epistemic contexts. An alternative view which recognises the function of mythological disciplinary narratives is proposed. This conceptualisation acknowledges that disciplinary discourses are only fully meaningful in their authentic contexts and emphasises the role of pedagogy in bridging the meaning that is made between agential participants in the different contexts. The fully elaborated model for forms of knowledge within the educational context locates a realist theory of knowledge within sociocultural theory and provides an epistemological account of students' relationships with disciplinary knowledge. It provides a theoretical tool for practitioners and those engaged in curriculum development for thinking about students' engagement with disciplinary knowledge. Implications for aspects of policy and practice are discussed, as are opportunities for further research.