jats:titleAbstract</jats:title>jats:pThis article frames a themed collection on Nationalism and Self‐determination in the Horn of Africa. It demonstrates how the praxis of self‐determination in the Horn of Africa has contributed to normative developments. On the basis of case studies of Eritrea, Ethiopia, Somalia and Sudan/South Sudan this article argues that nationalism and self‐determination have had different meanings in the political cultures across the different countries and have changed over time. We contend that such indeterminacy is unavoidable and should be welcomed. Nationalism is driven by historical circumstances that are contingent and often transitory. Self‐determination claims based on such nationalism are equally contingent and transitory. When the principle of self‐determination gets translated into concrete legal entitlements (for instance, a referendum on independence), it tends to solve one problem only by creating others. Instead, the pursuit and realization of self‐determination require constant political processes.</jats:p>