The Norwegian Association for Heredity Research played a key role in the rise of genetics as a research field in Norway. The immediate background of its establishment in 1919 was the need for an organization that could clarify scientific issues regarding eugenics and coordinate Norwegian representation in the organized international eugenics movement. The Association never assumed this role. Instead, Norway was represented in the international eugenics movement by the so-called Norwegian Consultative Eugenics Commission, whose leader, Jon Alfred Mjøen, was dismissed as a pseudo-scientist by Norwegian geneticists. The paper explores the Association’s role in defining and delimiting scientific expert knowledge in the field of genetics and eugenics in Norway. It demonstrates how struggles about academic authority on the national arena were intertwined with struggles about representation and impact in the international eugenics movement and how transnational scientific networks where mobilized to legitimize and delegitimize notions about Nordic race supremacy, racial mixing and the politics of eugenic sterilizations.