We conduct an online survey experiment among 8,000 respondents in Germany, Sweden, Italy, and Hungary to examine how information about migration-related terrorist attacks shapes public willingness to support or engage in various forms of political action. Our experimental manipulation will randomise information about the identity of perpetrators and victims of terror attacks (refugees and locals, in a 2x2 design). Outcome indicators consist of both attitudinal and behavioral measures. First, we are interested in how such information affects the willingness of the host population to participate in a rally in support of or against migrants; to sign a petition in support of or against migrants; to vote for political parties that are in favour of migration and against it; to donate money to NGOs that promote migrants right compared to NGOs that promote the welfare of the native population. We will also ask broader attitudinal questions about support for democracy, human rights, and compliance with international agreements related to treatment of migrants. Second, we will explore a behavioural response by allocating 1 euro to some respondents, and then asking them to choose whether to donate the money to an NGO that helps migrants, to an NGO that helps the native population, or to keep it to themselves. This survey is fully funded by CIVICA (an alliance of 8 European Universities), and is planned to be fielded in January 2022.