Discussing the Islamic State on Twitter Chapter 1: Introduction Chapter 2: The research methodology Chapter 3: Detecting the Sentiment towards IS and its evolution Chapter 4: A thematic study of the topics in the pro IS and anti IS tweets Chapter 5: The enemy of my enemy Hostility and sectarian discourse between pro IS and anti IS Arabic speaking Twitter users Chapter 6: Conclusion. This book explores how ordinary Arab speaking social media users have reacted to propaganda from the Islamic State rather than how IS propaganda has targeted ordinary users thus providing a change in perspective in the literature. The authors provide a comprehensive account of the evolution of the Arabic discourse on IS encompassing all phases of the Caliphate’s political evolution from the apogee of the Islamic State in October 2014 to the loss of its unofficial capital of Raqqa in September 2017. Taking into account key events the book also considers the most recurrent topics for IS and its opponents who engage in the Twitter conversation. The analysis is based on around 29 million tweets written in the Arabic language representing a random sample of around one third of all Arabic tweets referring to IS over the 2014 2017 timeframe. Matteo Colombo is Junior Research Fellow at the Clingendael Institute The Netherlands and Associate Research Fellow in the Italian Institute for International Political Studies (ISPI). He obtained a PhD in Political Studies at the University of Milan Italy. His main interests are in social media political reforms jihadism and energy policy in the Middle East. Luigi Curini is Professor in Political Science in the Department of Social and Political Sciences at the University of Milan Italy. His research focuses on party competition comparative politics quantitative methods machine learning and text analytics. He has published over 50 articles in international academic peer reviewed journals such as Comparative Political Studies Journal of Politics British Journal of Political Science European Journal of Political Research among others. He is also author of seven books and co editor of The SAGE Handbook of Research Methods in Political Science and International Relations (with Robert J. Franzese 2020).