This ERC project breaks the new grounds in the politico-economic literature on diversity, culture, conflict, and media by documenting social, economic, and political factors influencing the formation of group identification, behavior, and beliefs of different groups. The research conducted within the project examines the roots and the salience of different aspects of group identity and examines how different groups interact. Three pillars of the project focus on the role of social, economic, and political factors, respectively. The project uses the state-of-the-art empirical tools on large masses of data both in historical and contemporary experimental and quasi-experimental settings. Historical data are used to identify causal links in social-science questions, in which causality is notoriously hard to determine. The project sheds new light on the interplay of the economic shocks with political uncertainty in sparking mass ethnic violence using the setting of anti-Jewish pogroms in the Russian empire over the 19th century. The project is the first to credibly show that forced migration changes self-identification of displaced populations by documenting the effect of the expulsion of millions of Poles from the territories that Poland lost to the USSR after WWII. The project also documents a horizontal cultural slipover from forced migrants to the local population in the destination locations of forcibly displaced; we study this issue using the experimental variation created by Stalin’s deportations of Soviet Germans and Chechens to Central Asia during WWII. Using data on recently declassified secret police reports in the USSR, we are the first to document how the empowerment of local ethnicities in Central Asia in the 1920s helped Bolsheviks to reduce conflict and insergency and keep control over this large territory. We also use various contemporary settings, such as the Israeli-Palestinian conflict and the rise of the extreme-right populists in Poland and in France to document the effects of the information manipulations as well as the correction of the misinformation through media and directly on people’s attitudes, including for the deeply-rooted cultural traits, such as religiosity.