Rosetta Lulah Leavy was born in July 1871 at San Francisco, USA, the daughter of Francesca Simon and her husband, Charles Maurice Leavy, a civil service commissioner for the state of California. Rosetta received a bachelor of philosophy from the University of California in 1891 and then reputedly became the first woman teacher in a Californian high school.
She met her first husband, Frederick Ehrenfried Baume, a leading barrister (and later Liberal member of Parliament) from Auckland, New Zealand, when he visited San Francisco in 1898. After their marriage there on 21 June 1899, they went to live in Auckland, where they were to have four sons, one of whom died in infancy. Rosetta Baume was seen as a welcome addition to society – 'a brilliant conversationalist' and 'very accomplished'. However, she found New Zealand life 'provincial' and herself as an American university woman an oddity.
In 1910 Frederick Baume died in Germany, where Rosetta had accompanied him on a desperate search for a cure for heart disease. She and her three sons were left in reduced financial circumstances. After visiting San Francisco with them from 1911 to 1913, she settled down to vigorous educational and community work in Auckland. The first woman to be appointed to the Auckland Education Board and the Auckland Grammar School Board, she was also on the board of the Elam School of Art and the Auckland Technical School. She was a member of the Workers' Educational Association's district council in Auckland, honorary secretary of the Auckland Association for the Advancement of Education, and a member of the Auckland Town-planning League.
Rosetta Baume was also on the local committees of several women's and children's organisations, such as the Auckland branch of the New Zealand Society for the Protection of Women and Children, and was the first honorary secretary of the Auckland Women's Patriotic League. During the 1918 influenza epidemic she acted as president of the Auckland centre of the Women's National Reserve of New Zealand, which provided food for people in distress. From 1918 to 1920 she was a vice president of the revived National Council of Women of New Zealand and in 1919 she was a founder and committee member of the Auckland Women's Club. Her Princes Street home was the focus of much of this activity.
Her interest in women's participation in politics had begun to manifest itself in 1913 when, with Ellen Melville and Emily McGuire, she had helped to found and became first president of Auckland's Civic League, which aimed to increase the number of women holding public office. When legislation was passed enabling women to stand for Parliament in 1919, she and Melville 'felt it necessary to take the lead'. Baume stood in Parnell as an independent Liberal but, handicapped by her sex and the Liberals' general loss of electoral appeal, came third. Ellen Melville stood as a Reform candidate in Grey Lynn and came second.
Rosetta Baume believed that women members of Parliament should not be tied to any political party: each 'should be controlled only by her sense of right' and be free to help supplement 'our all too meagre social legislation'. She thought that women should present their policies on broad national lines and represent both sexes equally. Although she knew that women could advise men on many practical matters, she was aware that higher standards could be expected of women in public life: 'unlike men, women cannot make mistakes and recover public confidence'.
Concerned about the cost of living, she supported a motherhood endowment scheme, particularly to help poor people raising large families, and favoured increases in widows' and old-age pensions. She also wanted homes for children whose mothers were ill, homes and more schools for those who were mentally retarded, and a child welfare department to be established.
Although she felt the proper place for married women was in the home, she believed the role of single women in industry had to be recognised, and that equal pay should be given for equal work. Baume was a supporter of moderate labour, but was utterly opposed to the official 'revolutionary' New Zealand Labour Party. For instance, whereas she voluntarily appeared in the Court of Arbitration on behalf of women in unions, on one occasion, when she believed the workers' claims were exploitative, she represented the employers against them.
On 28 April 1921 at Rotorua, partly through concern that she would be a burden to her sons, Rosetta Baume married Edward William Kane, clerk of the House of Representatives. Her new home near Parliament in Wellington became a 'salon' where politicians and other leading members of society would gather.
She was soon invited to join the board of governors of Wellington College and Wellington Girls' College, on which she spent 11 years and rose to vice chair. She was a member of the Wellington branch of the League of Nations Union of New Zealand and of the Women's Service Guild, and a founder and committee member of the Wellington Women's Club. In 1931 she became a justice of the peace and a keen supporter of the justices' district association. That year she declined an approach to stand again for Parliament, but stated her intention of standing in the next election.
She died, however, on 22 February 1934 at Wellington, after a short illness, survived by her husband and three sons. It was said of Rosetta Baume that 'her broad and tolerant outlook, and the practical nature of her advice were highly valued by the many organisations with which she was connected'.