In this paper, I define and measure the new phenomenon of defensive citizenship in Europe. The literature suggests that defensive citizenship engagement is related to attempts by entitled citizens to preserve their threatened interests. It has been on the rise worldwide, especially in Europe. Based on studies and reports on the phenomenon, I argue that defensive citizenship can be assessed among entitled citizens (those born in the country, whose both parents were born in the country) based on mistrust toward political institutions, anti-immigration attitudes, and a challenging personal situation. Our analysis, based on European Social Survey data, ranks European countries and uncovers concentrations of counties with high levels of defensive citizenship in Eastern Europe. I contend that this phenomenon has significant implications for the democratic functioning of European countries and the stability of the continent.