Douglas A. Harper (born 1948) is an American sociologist and photographer. He is the holder of the Rev. Joseph A. Lauritis, C.S.Sp. Endowed Chair in Teaching with Technology at Duquesne University, a chair funded by a grant from the Mellon Foundation.
Harper was born in Saint Paul, Minnesota, United States. He earned a B.A. from Macalester College in 1970 and a Ph.D. in sociology from Brandeis University. While doing research for his Ph.D. dissertation about railroad tramps, he rode freight trains for 20,000 miles (32,000 km) in the western United States.