Wallerstein practiced medicine from an office in her New York home, and in 1905 founded a free clinic, the East Side Clinic for Children. She was president of the clinic for 25 years, until it closed in 1931. "There is no better-known clubwoman in New York than Mrs. Harry Wallerstein," noted the cover of
Broadway Weekly in 1904. She was president of the Woman's Legal Aid Society when it began in 1898, and president of the Adelaide Wallerstein Auxiliary of the National Army Relief Association for Porto Rico; the latter organization sent books, blankets, and disinfectants to American soldiers during the
Spanish–American War. During
World War I she organized a women's group to assist the Marines. She was also active in the
Daughters of the American Revolution and the
Women's Press Club of New York. Adelaide Wallerstein was president of the Rubenstein Club, from 1904 until a controversial ouster in 1909. In response, she founded the New York Mozart Society; the society's chorus performed at the White House in 1911, with
Arthur Claassen conducting. She was president of the Mozart Society from 1909 to 1937. == Personal life ==