Adler returned to America in 1873, and became a professor of Hebrew and Oriental Literature at Cornell University. Also in 1873 he delivered his first and only address to the Temple Emanu-El, entitled "The Judaism of the Future", which proposed ridding the religion of its superstitious traditions in order to better focus on the ethics which he felt was central to any human community. The congregation was receptive to his emphasis on ethics, but they were not about to cast aside three thousand years of tradition for the sake of one young man's bright idea. Adler soon found himself on the outside, cast to the margins.
In 1876, Adler founded the New York Society for Ethical Culture, and in the ensuing years played a major part in the establishment of other Ethical Societies across the country. He remained the moral and spiritual leader of the Ethical Movement until his death in 1933.
Adlers achievements were not limited to Ethical Culture, nor would you expect them to be, given his philosophy of active moral engagement with the world. He was an educational pioneer, founding the Ethical Culture Schools in Manhattan and Fieldston in the Bronx. He started the first free kindergarten in America. He was a champion of social reforms, including the establishment of model low-income housing and the abolition of child labor. And although he was a pacifist by nature, he was not opposed to American involvement in the First World War.
Adler wrote much, and lectured even more, but his published material is relatively sparse. An Ethical Philosophy of Life is a systematic unfolding of his ideas. The Reconstruction of the Spiritual Ideal is the collection of the prestigious Hibbert Lectures he gave at Oxford in 1923. These books and others are available through the American Ethical Union.