A deteriorating security environment has led to a renewed interest in understanding individuals’ willingness to fight for their country. This study examines how attitudes towards military conscription service differ between native-born youth and those with an immigrant background in Sweden, with a specific focus on differences between first- and second-generation immigrants. Using population-wide data linking responses from a mandatory survey with high-quality administrative registers, the analysis covers nearly all Swedish citizens born between 2000 and 2004. The results show that first and second-generation immigrants have very different attitudes towards military service. While first-generation immigrants are equally, or even slightly more, willing than natives to serve in the military, second-generation immigrants are considerably less positive. These differences persist even after adjusting for socioeconomic background and migration origin, challenging a common assumption in migration research that children of immigrants converge towards majority-group attitudes across generations. Further research is needed to understand the mechanisms behind second-generation immigrants’ lower willingness to serve.