Pelletier originally trained as an anthropologist studying the relationship between skull size and intelligence after Paul Broca with Charles Letourneau and Léonce Manouvrier. When she left anthropology she attacked the concept of skull size as a determinant of intelligence distinguishing the sexes. Following her break with anthropology Pelletier went on to become a psychiatrist. In 1903, Pelletier conducted a campaign with the support of the feminist newspaper La Fronde to support the eligibility of women for all types of medical specialisation, most relevantly to the examination for psychiatric internships. In 1906, Pelletier alongside Constance Pascal became two of the first French women to sit the examination to become a psychiatrists; they were also the first women to work as interns in state asylums. Outside her professional life, Pelletier was a committed activist. As a teenager, Pelletier attended feminist and anarchist groups. By 1900, Pelletier was actively involved in feminism and socialist activism. In 1906, she became secretary of La Solidarité des femmes, and established the organization as one of the most radical feminist organizations at the time. In 1908 she represented the group at the Hyde Park demonstrations for women’s suffrage. She published La suffragiste. During this period, in 1905, she also helped to found the unified French Socialist Party, sat on its national council until World War I, and represented the party at most international socialist congresses before the War. She worked for the Red Cross during the War, treating the injured from both sides. She was also notable as a female Freemason. Pelletier was a member of the La Nouvelle Jérusalemlodge, becoming a member in 1904. The lodge had both male and female members, and, although politically active, she was often at odds with her lodge in her efforts to promote the emancipation of women. Her views in favor of birth control and abortion were closely aligned with the French neo-Malthusian movement, supporting the use of birth control and abortion by women, she also wrote for the periodical Le Néo-Malthusian. Pelletier wrote extensively on the subject of women's rights, some publications include: La femme en lutte pour ses droits , Idéologie d'hier: Dieu, la morale, la patrie , L'émancipation sexuelle de la femme , Le Droit à l'avortement , and L'éducation féministe des filles . Pelletier displayed her beliefs in her dress and social behavior. She wore her hair short and was known for her cross-dressing and celibacy. Her actions were perceived by her contemporaries as a challenge to gender-identity. She wrote of her image, "I will show off mine when men adopt a special sort of trouser to show off their...". She traveled illegally to the Soviet Union in 1921, wrote Mon voyage aventureux en Russie communiste, first published in La Voix de la Femme at the end of 1921, and published as a separate volume in 1922. She joined the French Communist Party upon its creation, but left it in 1926; following her break with Communism she embraced Anarchism. Pelletier wrote utopian novels following her return from the Soviet state, as well as her autobiography La femme vierge in 1933. Pelletier was partially paralyzed by a stroke in 1937. However, she continued to openly practice abortion, and was arrested in 1939. Following her arrest she was interned in an asylum and her physical and mental health deteriorated. She died within the year.
