This article seeks to analyse how epistemic work (Alasuutari, 2018; Alasuutari and Qadir, 2019) in Portuguese parliamentary education debates develops through externalisation to world situations (Schriewer, 1990) whose references are used as epistemic capital (Alasuutari, 2018). The study explores debates occurring during Legislature X (2005-2009), in which the number of external references in plenary education debates significantly peaked compared with previous and subsequent legislatures. The analysis demonstrates that there was a change in the (de-)legitimation strategies policymakers used during this legislature. In addition to using the traditional ideological principles associated with each party, deputies often opted to use international organisations and their instruments, alongside reference societies, as authoritative sources to strengthen arguments and persuade their audience of their validity. This suggests that parliamentary policymakers assume that these external elements are useful in earning support for their policy ideas and promoting reform proposals.