Fort Concho was abandoned as an active military post in 1889. In 1905 C. A. Broome formed the Fort Concho Realty Company and parceled off lots in his Fort Concho addition to San Angelo. At about the same time J. L. Millspaugh, another real-estate developer who had been a post trader during the fort's active years, attempted to persuade the newly incorporated city of San Angelo to purchase the old fort as a park site. Although Millspaugh's initial efforts were unsuccessful, the eastern third of the parade ground and other pieces of property were donated to the city in 1913. The Pocahontas Chapter of the Daughters of the American Revolution sought to have Fort Concho designated a state historic site, a goal accomplished in 1924, when a bronze plaque was placed on the parade ground.
By 1929 Ginevra Wood Carson had founded the organization that became the Fort Concho Museum. She launched her campaign to save the fort by purchasing, for $6,000, the original headquarters building, built in 1876 by request of Col. Benjamin H. Grierson, who was then the post commander. Over the next thirty years Mrs. Carson spearheaded efforts to develop and expand public ownership of the museum. During that time several projects were undertaken, including the purchase and renovation of the schoolhouse-chapel, the reconstruction of two enlisted-men's barracks in 1951, and the acquisition of the Ruffini office building. In 1961 Fort Concho was registered as a National Historical Landmark through the Historic Preservation Office of the National Park Service. At about the same time the fort was placed on the National Register of Historic Places and designated a Texas Historic Landmark. Then in 1967 Franklin G. Smith, an NPS staff member, submitted a three-phase master plan for long-range development, financing, and interpretation of the site. Under Smith's plan, a museum director was employed, additional staff positions and several new programs were established, and a consistent preservation and acquisition program was carried on. Although local businesses and clubs continued to occupy and use some of the old fort buildings, such as the barracks, the officers' quarters, and the old commissary, the grounds contained seventeen surviving period structures, and the two barracks reconstructions. Some of these were at least partially restored and used for museum exhibits by 1980.
In 1980 a new master plan was published by the Bell, Klein, and Hoffman architectural firm in Austin. The old post hospital, which had been damaged by fire in 1911 and subsequently demolished, was reconstructed. It is now part of the John and Sally Meadows Historical Complex. By 1989 the museum complex included sixteen original structures, six reconstructions, and a stabilized ruin, making it one of the best preserved frontier forts in the United States.
The Fort Concho Museum contains over 35,000 artifacts in its collections. Equipment and furnishings in one of the officers' quarters and a barracks replicate the interiors of such buildings during the post's active years. The restored post chapel is often utilized by area school children, who relive the days of the McGuffy readers and one-room schoolhouses. The museum maintains an education department and an archive and research library. Conventions are often held in the restored commissary building. The Fort Concho Museum Press produces a monthly periodical, the Fort Concho Members' Dispatch, and other publications. Living-history groups reenact the lives of White infantry and White and Black cavalry units on the Texas frontier. These units can be seen at Fort Concho during Fiesta Frontier Day (third Saturday in June), Fiestas Patrias (second weekend in September), Christmas at Old Fort Concho (first weekend in December), and special events throughout the year.