The Philosophy and Mechanical Principles of Osteopathy’ is one of the landmark works in the field of Osteopathy, written by its founder, Andrew Taylor Still. Still was an American surgeon and physician who turned his attention to developing a system of treatment less invasive than the conventional treatments of his day. He investigated many 19th century practices and was inspired by their relatively tame side-effects. He believed that manipulation of the muscular skeletal system was the key to alleviating many illnesses, and developed his techniques into what he called Osteopathy (Greek roots osteon- for bone and -pathos for suffering). He promoted his system widely and founded the American School of Osteopathy, the world’s first osteopathic school, in Missouri. We are republishing this work with a brand new introductory biography of the author.