This paper is concerned with the criteria that constitute professional and occupational knowledge in the case of engineering, nursing and teaching . It asks what counts as knowledge in these cases. It draws on Bernstein’s analysis to contrast a focus on the disciplines that these professions draw on with one concerned with the connection between concepts of a discipline and problems that arise in a profession’s practice. These questions arise in the context of a research project which is investigating the relationship between knowledge and its organization into the curriculum and the perceived labour market demands of the three occupational areas . The paper examines the implications of these different approaches for school and college curricula which are increasingly dominated by subjects combining occupational areas into new fields of study.