In today’s media systems, large numbers of ordinary citizens circulate political information with great regularity. As a consequence, false and misleading information, whether it originates with elites or non-elites, can become widely distributed—and quickly. Now, people may be more likely to encounter false and misleading information on a daily basis. So if we really want to get to the root of the problem of so-called “fake news” we need to better understand why so many people will readily share false and misleading information online. Exploring why, and with what effects, people share news about politics on social media is therefore an essential part of the broader debate about the relationship between the internet and democracy. The healthy functioning of liberal democracies relies upon citizens whose role is to learn about the social and political world, exchange information and opinions with fellow citizens, arrive at considered judgments about public affairs, and put these judgments into action as political behaviour. The problem is that we currently know very little about the motivations that drive people to share political news on social media and how these might be contributing to changes in our online civic culture. If we can learn more about the things people try to achieve when they share news online—and the extent to which these motivations might reinforce or undermine the distribution of false or misleading information—liberal democracies can start to think about how they can reduce important online harms. This report is the first to address these issues in Britain on the basis of a survey of the news sharing habits on social media of a representative sample of the British public.