That the distinctions between terrorism and extremism have become increasingly blurred is something of a truism, but there has been little systematic analysis of whether this is truly the case nor of its possible implications. This paper argues that there has been a recent convergence between these two concepts in British parliamentary discourse, reproducing the same signifiers and meanings for non-violent extremism as previously existed for terrorism. In doing so, the paper makes a threefold contribution: methodologically through utilising the underdeveloped approach of post-foundationalist discourse analysis (PFDA) and applying it to the field of terrorism studies; empirically through analysing all the discourse in 1,037 British parliamentary debates between 2010 and 2017; theoretically through drawing together post-foundationalism with Bourdieusian practice theory to show that this transformation of discourse has coincided with social practices of informal criminalization targeting non-violent extremism as if it were terrorism. This has important policy implications as it prescribes particular counter-terrorism practices associated with the hegemonic discourse of terrorism which, when extended to extremism, risk alienating, dehumanizing and motivating the very people deemed to be “at risk” of extremism. The paper illustrates these issues through a discussion of their application in the Prevent Strategy for Higher Education.