 Lanteri worked for a decade in the Public Assistance Bureau of Buenos Aires and in the Emergency Hospital and Dispensary.She campaigned actively for greater access to medical care for the poor early on, and founded a periodical, "Semana Médica", for the purpose.She established the Argentine Association of Free Thought in 1905, and remained active in women's rights causes, having joined Grierson, Alicia Moreau de Justo, and others in the establishment of the Center for Feminism at the 1906 International Congress of Free Thought, held in Buenos Aires.