Nationalism, or the sense of belonging to a nation, is a modern concept with ancient roots. It gained traction in the nineteenth century, especially in Central and Eastern Europe, and across the world as the phenomenon of the nation state became the prominent vehicle of identification in the wake of declining empires. In most cases, nationalism was pursued through peaceful and democratic means; most nationalists are not terrorists, nor do they resort to violence when political decisions are made against them. However, in some cases, nationalism as an ideology has served as the primary reason for using terrorism as a means of fighting against what is viewed as an illegitimate and powerful empire. This chapter investigates the linkages between nationalism and terrorism in this context, then discusses particular terrorist cases across the world, before focusing on the American context.