 Green became active in Liberal Party politics in the mid-1860s. In 1876 he was elected to the Oxford town council; he was the first don to serve as a representative of the citizens rather than the University of Oxford. His principal policy reforms concerned land reform, labor regulation, education, and temperance. He supported the Irish Land Act of 1881, which sought to secure property rights of peasant farmers in Ireland. In education, he argued that primary education should be compulsory and state-financed. He served as an assistant commissioner on the Taunton Commission on Secondary Education in 1865–66, arguing for significant reforms in education to equalize opportunity for higher education. He was a member of the Oxford School board and played a part in the foundation of the Oxford School for Boys. He was an important factor in the university extension movement, he sought to open university education to women, and he advocated the use of scholarships and other subsidies to make a university education available to the working classes.