Social media has emerged as the primary source of information for millions of people around the world. Unlike other, older media channels like newspapers or television, social media provides a chance for the public to engage directly with those shaping the political direction of their home, and vice versa. For all the potential these platforms have to create conversations between ruler and ruled, such discussions are dominated by one-sided and, at times, poisonous words—to the extent that the UK Parliament's Health and Wellbeing Service advised all Members of Parliament to quit Twitter in 2018. Why, though, is a near-universal experience? What are the origins—and consequences—of incivility on social media? This project aims to find out to what extent politicians create divisive posts on social media and if these politicians actually benefit from the uncivil comments they receive in response. Using data from Twitter and deploying experimental and automated text analysis methods, the project will measure affective polarisation and incivility. Online survey will then be used to model the reactions of the public to social media polarization and incivility.