If you are a frequent reader of newspapers, you might have come across articles in which tweets are directly cited as sources. This practice by journalists has become common since the emergence of Twitter as one of the most popular social media platforms, raising questions over the impact it is having on sourcing practices and the journalist-source relation. In this chapter, we investigate this phenomenon by analysing how Dutch journalists use Twitter as a source in political news coverage at four national dailies. We ask how, and to what extent, Twitter is contributing to the agenda-building process—the process by which news organisations and journalists determine what to cover. Through the use of a content analysis, we track and analyse the citation of tweets by focusing on the type of actors cited; the function cited tweets served in the news stories; the nature of the tweets cited (e.g. factual, opinion); and finally the dominant quoting practices. Our findings contribute to our understanding of the ways in which the use of Twitter shapes political news coverage.