This essay rethinks the gender history and historiography of interwar sub-Saharan Africa by deploying the heuristic device of the ‘modern girl’ to consider how global circuits of representation and commerce informed this period of gender tumult. This device has been developed by a research group at the University of Washington to understand the global emergence during the 1920s and 1930s of female figures identified by their cosmopolitan look, their explicit eroticism and their use of specific commodities. Previous scholarship has suggested that a black modern girl imbricated in international circuits of images, ideologies and commodities only became visible in southern Africa in the post-Second World War period. Yet, analysis of the black newspaper Bantu World reveals the emergence of such a figure by the early 1930s. The modern girl heuristic helps to situate race as a key category of analysis in scholarship on women and gender in interwar Africa as contemporaries consistently debated her in racial terms. In South Africa, some social observers saw African young women’s school education, professional careers and cosmopolitan look as contributing to ‘racial uplift’. Others accused the African modern girl of ‘prostituting’ her sex and race by imitating white, coloured or Indian women, and by delaying or avoiding marriage, dressing provocatively and engaging in premarital and inter-racial sex. Cosmetics use was one of the most contentious issues surrounding the black modern girl because it drew attention to the phenotypic dimensions of racial distinctions. By analysing a beauty contest in Bantu World together with articles and letters on, and advertisements for, cosmetics, this essay demonstrates how, in white-dominated segregationist South Africa, the modern girl emerged through and posed challenges to categories of race and respectability.