Harper is an unincorporated community and census-designated place (CDP), located 23 miles (37 km) west of Fredericksburg on U.S. Highway 290, in Gillespie County, in the U.S. state of Texas.

A historical marker just south of U.S. Highway 290 commemorates the McDonald massacre of August 1864.

This incident involved the killing of two family members and the kidnapping of five more by Kiowa Indians.

A post office was established in 1883 by George Franklin Harper, for whom the town was named.

By 1985, the town served a large ranching area and had six churches, a fire department and ambulance services, a public school, and growing residential subdivisions.

The climate in this area is characterized by hot, humid summers and generally mild to cool winters.