By 1898, the year Iowa legalized the practice of osteopathy, Still started his own school in Des Moines, the second such osteopathic school in the nation, with the help of his professional partner and wife, Ella Daugherty Still, a respected gynecologist and teacher. Their new S.S. Still College and Hospital of Osteopathy was first located at 1429 Locust St., and they also acquired a building across the street at 1422-28 Locust. The couple had married in 1877 and had two children, George, who became a surgeon, and Delia.
Still studied law at Drake University, receiving degrees in 1903 and 1904. Throughout his life, Still was known as a voracious reader and a wonderful conversationalist who could discuss a wide range of subjects. In 1905, Still sold his interests in the school and devoted himself to private practice until 1913. He then became an anatomy professor at the Kirksville school and, after his son's accidental gunshot death in 1922, succeeded him as president of the facility, serving two years. From 1924 on, Still contributed a column to the Kirksville Graphic newspaper, with his last column published the day of his death. The physician's body was brought back to Des Moines the next day for burial at Woodland Cemetery.