Summary: The approximately 1700 words entry identifies nationalism as a domain of historical case- oriented research, develops a typology of the plurality of approaches based on central questions asked in the literature, and contrasts diverse conceptions of what a nation is and how to define it. Central to the author s summary of the material is the idea that nationalism is an open concept, while a distinction is made between nationalism as an independent political idea and as part of most countries history. Geographical or periodical comparisons make up the first approach to understand the phenomenon of natioanlism, a second one analyses nationalism from a history of ideas point of view focusing on the development of European nation states. The third school typically investigates the goals of nationalist movements, while another one concentrates on the role and impact of nationalism for the individual psychic. Political scientists investigate nationalism within modernization theory in its societal role, whereas political economy scholarship connects nationalism to issues of inequality. Marxism, finally, ist identified as lacking a theory of nationalism due to its focus on classes instead of nations or states. According to the entry , the plurality of approaches is nmot the biggest problem, but rather the lack of a common understanding of central terms. Comparing a variety of criteria to identify what a nation is establishes the historical and geographical context- sensitivity of the concept. A brief reflection on the role of nationalism in international relations, and the increasing transnationalism at the end of the 20th century, concludes the entry.