Much research has sought to map the spread of extreme and populist political ideologies across Western Europe. Despite this, it o en fails to explain how these ideologies move from the political fringes to positions of in uence, subvert- ing the traditional cordon sanitaire around extreme views. As a result of recent successes by populist actors, a more nuanced understanding of this process is required. is paper posits an explanation for this success, suggesting that the grow- ing pluralisation of the online media environment and the impact of social media content sharing are key to understanding how fringe political actors avoid both overt and implicit barriers to popularising extreme positions. Using data from the British Election Study, this paper o ers a quantitative test of this approach, nding an inconsistent relationship between social media use and ex- treme political opinions. Potential explanations for this are discussed alongside possible directions for future research.