Abstract: This article examines the intersections of race, sex and gender that shaped the legal system of assimilation in colonial Mozambique. Between 1917 and 1961, Africans could apply for assimilated (assimilado/a) status, granting them limited rights of Portuguese citizenship. Analysis of assimilation case files, administrative reports and public debates in local newspapers reveals that assimilation was an ambiguous, changing and gendered system shaped not only by its Portuguese legislative architects, but also by the African men and women who navigated the law, and encouraged its reforms, over time. Using a feminist historical approach to challenge entrenched scholarly interpretations of the system as uniformly male gendered, this article reveals that marriage, miscegenation and women were at the centre of the assimilation system as a contested site of the politics of ‘civilisation’ in the colonial capital of Lourenço Marques.