Brock is on Farm Road 1543 eleven miles southwest of Weatherford in southwestern Parker County. In 1871 John Henry Brock purchased land in the area. In 1876 James M. Maddux, another prominent early settler, arrived from Arkansas. In 1880 Brock and Willie Brannon built a gin and mill at nearby Grissom Springs. Brock was a carpenter and cabinet maker who built a number of the early buildings in the community. Brock post office, named for John Brock, opened in the community in 1888. In 1892 the town contained a blacksmith shop, cotton gin, grist mill, grocery store, post office, and school. In the early 1890s the town added a flour mill and the Olive Branch Collegiate Institute. By 1900 Brock had an estimated 100 residents. Its post office was discontinued in 1919. Its population was reported as more than 100 until the 1940s, when it was ninety-five; it later dropped to twenty-five. In 1980 and 1990 Brock reported fifty-one residents. In 2000 the population was eighty.