American lawyer and clubwoman, a moving force in establishing national and international organizations to address the interests and concerns of business and professional women.

Phillips, who adopted the given names Lena Madesin at age 11, was educated at Jessamine Female Institute and at the Woman's College of Baltimore, Maryland (1899–1901; now Goucher College). Although she attended the Peabody Institute of Music in Baltimore for a time, an injury to her arm ended her dreams of a career as a concert pianist. Over the next decade she held various jobs, and in 1915, after suffering a nervous breakdown, she resolved to become a lawyer. Two years later she graduated from the University of Kentucky Law School. She soon became an attorney for the Young Women's Christian Association and secretary of its National War Work Council. In 1918 she was sent to New York City to organize the National Business Women's Committee for war work. Although the war ended before the committee was able to begin its work, the members decided to form a permanent peacetime organization for women in business and the professions.

Phillips organized a convention in St. Louis, Missouri, in July 1919 at which was formed the National Federation of Business and Professional Women's Clubs, and from then until 1923 she was executive secretary of the federation. While traveling widely to foster the establishment of local clubs, she helped found the federation's journal, Independent Woman, in 1920. In 1923, after receiving a master's degree in law from New York University, Phillips entered private practice in New York City. From 1926 to 1929 she served as president of the National Federation of Business and Professional Women's Clubs, and during that period she initiated the movement that culminated in the founding of the International Federation of Business and Professional Women (1930). She served as president of the International Federation from then until 1947. She was also president of the National Council of Women (1931–35), and in 1933 she was president of the International Conference of Women held in conjunction with the Chicago World's Fair.

Phillips abandoned her legal practice in 1935 and for four years thereafter was associate editor of and a columnist for the Pictorial Review. Her work as president of the International Federation required her to travel frequently to Europe, and during and after World War II she worked to sustain and rebuild clubs and national federations there. She was also active in war-relief work and the United Nations and later was chairman of the First International Conference on Public Information.