He was appointed a professor at Johns Hopkins University when it opened in 1876. He was a professor of Sanskrit at Hopkins from 1876 to 1880. In 1880 Lanman moved to Harvard University where he was the first to preside over the department of Indo-Iranian Languages, which became the department of Indic Philology in 1902, and ultimately became the department of Sanskrit and Indian Studies in 1951. (During 1911 and 1912 one of his students at the Harvard Graduate School was T. S. Eliot, who was undertaking a doctorate in philosophy.)