Atkinson was a prolific writer, and his many books achieved wide circulation among New Thought devotees and occult practitioners. He published under several pen names, including Magus Incognito, Theodore Sheldon, Theron Q. Dumont, Swami Panchadasi, Yogi Ramacharaka, Swami Bhakta Vishita, and probably other names not identified at present. The works published under the name of William Walker Atkinson generally treat themes related to the mental world, occultism, divination, psychic reality, and mankind's nature. They constitute a basis for what Atkinson called "New Psychology" or "New Thought." Due in part to Atkinson's intense personal secrecy and extensive use of pseudonyms, he is now largely forgotten, despite having obtained mention in past editions of Who's Who in America, Religious Leaders of America, and several similar publications - and having written more than 100 books in the last 30 years of his life. His works have remained in print more or less continuously since 1900.