"Diaspora", an old phenomenon, signifying dispersed people outside their homeland, who sustain their ties with their homeland and their co-ethnics, highly mobilized in politics in recent years, certainly in a new form. This thesis suggests the term “diaspora nationalism” for this unique phenomenon. As “diaspora nationalism” is based on the triadic relationship of homeland, host-state and diaspora community, it differentiates from mainstream nationalisms. While challenging the dominant conceptualizations of nationalism, in fact diaspora nationalism reconstructs nation and ethnicity in a global framework. Therefore it necessitates a new conceptual tool for fully appreciating its features. "Transnationalism", which is a new term to denote the relations across the borders, provides us with the adequate conceptual tool. The rising diaspora nationalism of the Crimean Tatars in recent years can only be fully apprehended in the light of this conceptual framework. With this conceptualization of diaspora nationalism, this study specifies, periodises, and tries to analyse the diaspora nationalism of the Crimean Tatars in Turkey, by also suggesting the case for further theoretical and historical inquiry. Having transnational and hybrid features, Crimean Tatar diaspora nationalism faces with different problems and find different solutions, which in the end contribute to the “new politics” in the global era.