After the foundation of the republic in 1923, Turkey inherited both the intellectual and institutional legacy of historical studies established in the late Ottoman period. A seeming milestone in converting Ottoman historical institutions to republican purposes came when the first professional historical association of the Ottoman realm, Tarih-i Osmani Encümeni (Ottoman Historical Society, founded in 1909), was renamed Türk Tarih Encümeni (Turkish Historical Society) in 1924. Yet although its name changed, Türk Tarih Encümeni retained Ottoman studies as its primary field of research until its abolition in 1931. Ironically, the society was abolished because of its exclusive focus on Ottoman history. Its place was taken that same year by the Turcocentric Türk Tarihi Tedkik Heyeti (Commission for the Study of Turkish History), later renamed Türk Tarih Kurumu (Turkish Historical Association). However, many members of the former Ottoman Historical Society joined the new historical association. It had also acquired the library collections of the former institution. The establishment of a formally identical institution with an agenda of dismantling the dominance of Ottoman history over the broader history of the Turks represented a shift in the republican mindset, but one that developed gradually and retained clear vestiges of the Ottoman institutional past. This paper explores the process of the transformation of the Ottoman Historical Society into the Turkish Historical Society. It delves further into the dichotomous nature of the early Turkish Republic’s repurposing of late Ottoman institutions. While the early Republican historians absorbed the positivist agenda of the late Ottoman historical institutions, which put the history writing into a broader global historiographical framework, they modified this agenda to provide a legitimate base for nationalist theses arguing that Turks are descendants of the first human civilizations and a homogeneous Aryan race. Ultimately this paper argues that the Republican institutions utilized these very agendas of the late Ottoman historical institutions in order to “de-Ottomanize” the history writing, meaning to sever the Republic’s relationship to its immediate Ottoman past.