Wood stood unsuccessfully as a parliamentary candidate for East Islington in 1895, Glasgow St. Rollox in 1900 and Orkney and Shetland in 1902. However, in 1906 he was elected for Glasgow St Rollox as a Liberal, a seat he held until 1918. In April 1908 Wood was appointed Parliamentary Secretary to the Board of Education in the administration of H. H. Asquith, a post he held until October of the same year, when he became Under-Secretary of State for Foreign Affairs.