This paper intends to focus on the Turkish eugenics movement in Turkey in the 1920s and 1930s within a comparative perspective. As an international movement of the turn of the 20th century, eugenic movements turned out to be very influential and widespread especially in North America and Europe. Turkey was not an exception and the rise of eugenics in Turkey was in part a response to the young Republic's problem of population after the long wars of World War I and the War of Independence. The need to increase the population and the biological "quality" of the population became a central theme in Turkey as well as in many other countries. However, eugenics encompasses many other important themes such as the role of science and values in the making of nationalism, the "governing" of the population, social engineering and welfare state, the question of nature vs nurture, the hegemony of the middle class values and the so-called racial degeneration. Within this wider context, this paper aims to focus on some of the central themes and practices concerning eugenics in Turkey of the single-party regime (1923-1946). My goal is not to offer simply a presentation of the characteristics of the Turkish case, but to contextualize it within a comparative perspective. By so doing, I aim to look at Turkish nationalism on the basis of a much more "material" basis and to contribute to the understanding of nationalism beyond simple discoursive models mostly based on the elite perceptions. The Turkish case is interesting in the sense that eugenics, though it existed, was not pushed into the extremes. To support my arguments, I use many primary sources such as the conferences held by the governing Republican People's Party, the Party reports and publications such as Ulku, many journals and conference proceedings of Turkish doctors such as Milli Tip Kongreleri (Annual National Congresses of Medicine), memoirs of doctors and the political elite and many journals from the era such as Yeni Adam, Kadro and Resimli Ay. Benefiting from these primary sources and from the huge literature on eugenics in the world, this paper aims to contribute a comparative perspective using the Turkish case. Taking into consideration the rise of hereditary ideas and practises based on genetics of our contemporary world, such comparative perspectives can be useful not only to understand the past, but the present as well.