In this article, we analyse how educational policy debates regarding specific school subjectsare related to the demarcation of science. Utilising boundary-work theory we analyse materialfrom a later abandoned revision process for the Swedish upper secondary school curriculumin 2004–2006. During this process a new subject – Sustainable Development – was proposedby the Swedish National Agency for Education. As a consequence, the Geography subject,potentially a suitable arena to naturally handle education for sustainable development, wouldbe given a very peripheral role in the upper secondary school curriculum. From the sugges-tion a debate about scientific boundaries arose, with arguments that may be traced back tothe theoretical concepts; ‘exclusion’, ‘expansion’ and ‘protection of autonomy’.