Based upon research undertaken in Turkey, Russia, Azerbaijan, and the Crimea, this article consists of three principal and interconnected fields of inquiry. The first focuses upon changing Russian and Ottoman policies toward the immigration of Russian Muslims to the Ottoman Empire in the second half of the 19th century. The second examines questions that complicate the historiographical narrative surrounding this immigration, including issues such as Muslim return immigration to Russia and the retention of Russian citizenship by Muslim immigrants in the Ottoman Empire. The third examines the increasingly contested nature of citizenship and its role in the relations between Russian Muslims and the Russian and Ottoman bureaucracies. This section investigates battles between Ottoman and Russian bureaucrats who assert authority over Muslims of ambiguous citizenship status and the strategies deployed by Russian Muslims to take advantage of this ambiguity in their dealings with the bureaucracies of both empires.