In 1916, Weizmann gave up her work as a pediatrician when she joined her husband upon his appointment as the scientific adviser in chemistry to the British Admiralty during the First World War. In 1920, she was one of the founding members of the Women's International Zionist Organization (WIZO), and served as its president, alternating with Lady Sieff, for forty years. When the Second World War broke out in 1939, she devoted all of her efforts to Youth Aliyah ("Aliyat Hanoar"), an organization that she established in England and continued to head as honorary president while living in Israel.