This article is the result of a grounded theory investigation into the ways PhD topics are assigned by supervisors in engineering and selected by students in the social sciences/humanities in UK universities, broadly referred to as ‘topic arrangement’, which can be regarded as one aspect of academic socialisation into academic Discourse communities. Interview data was collected from thirteen Iranian PhD students studying in different UK universities and six of their supervisors during 2000–2001. One further interview was conducted with a professor of sociology. The interviews were transcribed, thematically coded, and analysed using NUD.IST. The results show that PhD students themselves often select PhD topics in the social sciences/humanities, whereas PhD topics are often assigned to PhD students by engineering supervisors. The reason for this difference in practice between these two fields seems to stem from different ideologies on what constitutes a PhD across disciplines, as well as funded projects, which are more likely to be available to engineering supervisors and students. Throughout the paper, a modest attempt has been made to draw the attention of EAP practitioners to a redefinition of the concept of Discourse with a big ‘D’, which includes linguistic and non-linguistic aspects of advanced academic literacy.