Darlington Agency, Historic district in Canadian County, United States

The Darlington Agency is a former Bureau of Indian Affairs agency site on the Cheyenne and Arapaho Reservation, in what is now Canadian County, Oklahoma, at 35°34′31″N 98°0′32″W. It was founded in 1870 to replace an agency opened the year before at Fort Supply, and was named for Brinton Darlington, a Quaker who served as its first U.S. Indian agent until his death in 1872. The site was listed on the National Register of Historic Places on August 14, 1973.

The Darlington Agency was established in 1870 on the Cheyenne and Arapaho Reservation, replacing an agency opened the year before at Fort Supply so the tribes could reach it more easily. It was named for Brinton Darlington, a Quaker who served as its first U.S. Indian agent until his death in 1872. In 1877 Dull Knife and about 900 Cheyenne were interned here; most escaped the next year and were recaptured and brought back. The Cheyenne left for their own agency at Concho in 1897, and the Arapaho later joined them there.

The agency's name honours Brinton Darlington, a Quaker who served as its first US Indian agent until his death in 1872. His daughter Elma and son-in-law Jesse Townsend opened a day school there, and John Homer Seger later ran the Indian school, which an 1876 inspection counted 115 pupils. From 1880 the Cheyenne Transporter, the first newspaper in western Indian Territory, was printed at the agency.

The former agency site lies in Canadian County, Oklahoma, at the coordinates 35°34′31″N 98°0′32″W, on the south side of the North Canadian River near Fort Reno. It is now the Darlington State Game Farm, run by the Oklahoma Department of Wildlife Conservation as a bird hatchery and research station, so access follows the facility's own arrangements rather than a visitor centre.

The site is now the Oklahoma Department of Wildlife Conservation's main bird hatchery and research station, renamed the Darlington State Game Farm. Before that, the state used it briefly as a drug rehabilitation center, and the Masons ran a boarding school and retirement home there until 1922.