This paper aims to analyze the problematization of eugenics and neo-Malthusian thought in Brazilian anarchism through the texts present in the book Amai e não vos Multipliqueis (1932) and in Renascença magazine (1923) of the libertarian and feminist Maria Lacerda de Moura. The analysis will look at the observations of Álvaro Sierra in Darwinismo Social e Izquierda Política (2005) regarding the importance of making a social history of the appropriation of scientific and technological knowledge that tries to perceive the processes of transformation of this knowledge in popular classes. A social history of science and technology that is aware of the specificities of the political subculture, such as the anarchist, and whose premise is the plurality of the “political culture of the popular classes”. Therefore, when we consider in the anarchist ideology the central character of the role of science as emancipating and revolutionary, it becomes fundamental a view of the political culture which, by adopting an interdisciplinary attitude, allows the perception of the narratives and libertarian social practices on such themes as technology, eugenics, neo-Malthusianism, sexuality and vivisection. Such themes permeate Moura's literary works and political articles. In the analysis of the narratives we will use the methodological care, indicated by Richard Cleminson in his study Eugenics without the state (2008), of refusing to assume essentialist notions of science and technology, and worrying about defining them through the concepts proposed by the anarchists themselves. Put differently, the concepts and practices that involve science and technology will be understood in the national historical context of the actual social movements, and its political and ideological struggles. Cleminson demonstrates in his analysis the importance of this approach by stressing that contrarily to the common sense definition of eugenics as rightist, racist and linked to the state, several anarchists appropriated the concept of eugenics, contradictorily, as a critical instrument to capitalism, a way to strengthen the living conditions of the working class and to exercise conscious sexual freedom. We will see in the texts of Moura the defense of the adoption of neo-Malthusian techniques as a constituent element of the “conscious maternity”, central to the libertarian project of the female emancipation.