He received his PhD in Modern History from the same university in 2010. His research concentrates on decolonization after 1945 and the postcolonial societies of Europe, especially France and Portugal. His first book was published by Cambridge UP in 2016 (originally published in German in 2011). Entitled ‘The Discovery of the Third World: Decolonization and the Rise of the New Left in France, c. 1950-1976,’ it deals with the interconnection between the rise of the concept of the "Third World" and that of a new radical left in France. Currently, Christoph Kalter is pursuing his interest in postcolonial Europe in a second book-length project, entitled ‘Postcolonial People. Migration and Decolonization in Portugal, c. 1974-2014,’ which addresses the history of decolonization in the metropole through a focus on the so-called retornados.