From 1927 to 1932, she worked as a social worker, including at the Wardell Commission on Social Welfare and the Foster Home Bureau of Hebrew Sheltering Guardian Society. From 1929 to 1945, she served on the board of the Madison Settlement House, and from 1930 to 1935, she served as a commissioner on the New York City Board of Child Welfare.[1][2]
In 1936, she became the first woman to work at the law firm of Cravath, Swaine & Moore but left after a year because of the impending birth of one of her children. In 1937, she became one of the first women admitted to the New York City Bar Association. Also in 1937, she began a half-century association with the Legal Aid Society (first woman chairman 1979–1983). In 1942, she became a 20-year trustee of the Dalton School. In 1947 (to 1950), she became first chairwoman of a standing committee of the Bar Association of the City of New York. In 1949, she became the first female bank director, as trustee of the Title Guarantee and Trust Company. Also, from 1949 to 1950, she was a member of the civil rights committee of the New York State Bar Association. From 1949 through 1980, she served as a trustee of Connecticut College.[1][2]
Around 1940, she founded her own law firm, Brennan, London and Buttenwieser. The Jewish CFromld Care Association was a client from 1940 to 1975.
In 1947, she co-founded Beer, Richards, Lane, Haller & Buttenwieser, 1947–1959[4][5]Harold Rosenwald (one of the first lawyers to join the Alger Hiss defense team) was a member of the firm.[6]
In 1929, she married Benjamin Buttenwieser, a prominent banker and philanthropist and son of attorney Joseph L. Buttenwieser. She left Cravath after a year because of the impending birth of a child.[1]