Moser was born into a wealthy, bourgeois family and grew up in various places including southern Germany and Switzerland. In 1891, she began studying zoology at the University of Zurich and then in London. In Great Britain, she became increasingly interested in modern approaches to social policy and social welfare. Influenced by the progressive Anglo-American workers' settlement movement, Moser worked in a London social settlement after 1898 and completed a two-year practical training programme in social work. Once she returned to Switzerland in 1903, she remained committed to socio-political issues. She gave lectures, wrote short articles, founded an association for the blind as well as the first welfare office for tuberculosis patients in Zurich and became involved in planning workers’ settlements in Zurich. At odds with the traditionalist poor relief in Zurich, she initiated Anglo-American-inspired women’s welfare courses with other female campaigners in 1907; these later merged to form the Zurich School for Social Work. Moser left the project in 1908 due to political differences. During this time, she considered herself a socialist and established contacts with the left wing of the social democrats. Following the October Revolution, she sympathised with communism and was a founding member of the Communist Party of Switzerland in 1921. She worked for Pro Juventute in the early 1920s. She managed the care of mothers and infants and set up a counselling centre for contraception in Zurich. In addition, she increasingly committed herself for women's suffrage rights. Her political convictions prompted her to visit several countries from the mid-1920s on. She visited the Soviet Union on various occasions, where she invested a portion of her inheritance to open an international children’s home for orphaned children near Moscow in 1929. At the beginning of the 1930s, she spent an extended period of time in Berlin and became ensnared in militant altercations between national socialists and communists. She fled from Berlin to Switzerland in 1934, where she waited out the Second World War. After the war, her communist contacts brought her to the German Democratic Republic (GDR). On the invitation of Wilhelm Pieck, the country’s first president, she moved to East Berlin in the 1950s, where she remained until her death in 1971.