This dissertation explores the legacy of African slavery on the ideas about citizenship and race in the late Ottoman Empire and early Turkish Republic. Even though the conventional Ottoman historiography of the nineteenth century and Turkish studies on the early Republican period tend to demonstrate the operation of nationalism through ethnic and religious differences, I argue that race constituted an important aspect of mechanisms of differentiation of the time. By unpacking the entangled histories of blackness and slavery from the ban on African slave trade in 1857 until the abolition of the institution in 1933, my research problematizes the joint formulation of racial and national identity in the late Ottoman Empire and early Turkish Republic.Based on diverse sources such as slave petitions, manumission papers, legal records, treaties, consulates correspondences, parliamentary minutes, newspapers and memoirs, the body of the dissertation investigates the ethnic/racial identity formation, definition of Ottoman/ Turkish citizenship and operation of race in late Ottoman empire and early republican Turkey. My dissertation, firstly, challenges the limits of the historiography on Turkish nationalism that has so far privileged ethnic and religious minorities in relation to identity crises. Secondly, it uncovers the silence around the history of slavery both in the Ottoman historiography and in the official memory of the modern state. It argues that a scholarly inquiry about the Ottoman slavery, particularly with a focus on African slavery would bring an alternate perspective- a truly subaltern perspective- to the Ottoman historiography. Finally, it expands the current discourse on African Diaspora by pointing out the impact of locality on the formation of multiple diasporic identities.