The present article extends Basil Bernstein's theorisation of "discourses" and "knowledge structures" to explore the potential of educational knowledge structures to enable or constrain cumulative learning, where students can transfer knowledge across contexts and build knowledge over time. It offers a means of overcoming dichotomies in Bernstein's model by conceptualising knowledge in terms of "legitimation codes" (bases of achievement) and "semantic gravity" (context-dependency of knowledge). This developed framework is used to analyse two contrasting examples of curriculum--from professional education at university and secondary school English--that aim to enable cumulative learning. Analyses of students' work products show that both cases can constrain knowledge-building by anchoring meaning within its context of acquisition. The basis for this potential is located in a mismatch between their aims of enabling students to learn higher-order principles and their curricular means that focus on knowers' dispositions rather than articulating principles of knowledge. (Contains 3 figures, 2 tables, and 5 notes.)