Mosa Anderson was associated with the Save the Children Fund for many years, serving as a member of its Council 1933-1967. In 1916, on her return from Paris where as an accomplished linguist she had been studying Russian, she was asked by Dorothy Buxton to assist in the production of the 'Cambridge Magazine' which ran articles translated from foreign newspapers. In this capacity she acted as a Russian language translator. After the foundation of the Save the Children Fund in 1919 she moved to Manchester to continue with 'Notes from the Foreign Press' which had been taken over by the 'Manchester Guardian', and continued presiding over the editorial work until the end of 1921. Mosa Anderson attended a SCF Summer School and an Esperanto Conference in Geneva in the 1920s. In 1923, then in London, she became secretary to Charles Roden Buxton, MP, husband of Dorothy Buxton, Eglantyne Jebb's sister, joining him in investigating the situation of German refugees in France in the 1930s.
During World War II she worked on the establishment of residential nurseries in Britain and later, in April 1946, she went to Poland to organise post-war relief work, spending some 11 months there. She later worked in Germany.
Mosa Anderson was also a member of the Women's International
League for Peace and Freedom; and was the author of several books including
'German and Europe's Future (National Peace Council, 1946), 'Noel Buxton: A
Life' in 1952 (Noel Buxton was Dorothy Buxton's brother in law), and 'Henry
Joseph Wilson: Fighter for Freedom' in 1953.