The Star of the Republic Museum, located at Washington-on-the-Brazos State Historic Site, commemorates the site of the signing of the Texas Declaration of Independence and of the last capital of the Republic of Texas. The museum building is a star-shaped, two-level, 22,000-square-foot facility built in 1969. The campaign to construct a commemorative museum or structure in the park began in 1955 when several members of the Brenham Chamber of Commerce formed the Texas Independence Day Organization. In addition to sponsoring the annual Texas Independence Day Celebration, the group began raising funds to develop the park and to construct a museum. A statewide campaign to raise $1 million was funded in 1962 by Mary Moody Northen of Galveston, but it was subsequently abandoned. In 1966, under the leadership of George Red, the group was reorganized into the Washington-on-the-Brazos State Park Association and, with the aid of State Representative Gus Mutscher of Brenham, requested and received state appropriations of $800,000 to finance park improvements and a museum. A donation of $200,000 from the Houston Endowment, Incorporated, an additional state appropriation in 1968, and numerous private contributions provided further funding. Under the leadership of George Butler the association worked with the State Building Commission on the design and construction of the museum. Upon completion, the museum was transferred from the State Building Commission to the Texas Parks and Wildlife Department. In September 1969 the museum was placed under the administration of Blinn College, Brenham. It was officially dedicated and opened to the public on March 1, 1970.
John P. Landers was employed by Blinn College as the museum's first director. During his administration (1970–72), he began assembling collections of Texas furniture, decorative arts, and documents. Director John W. Crain (1972–76) enlarged the museum's manuscript, document, and map collections; he also initiated a program of art and temporary exhibitions, and from 1972 to 1977 the museum displayed about twenty temporary exhibitions annually. Under the directorship of D. Ryan Smith (1977–87) the museum concentrated on installing major permanent exhibits with one or two temporary exhibits each year. Houston McGaugh assumed the directorship in 1987. The Blinn College board of trustees formally adopted and endorsed the Star of the Republic Museum's name and purpose in 1979. The institution had been variously known as Washington State Park Museum or Old Washington Museum.
The museum interprets the history of the Republic of Texas through exhibits, programs for visiting groups, media programs, and community activities. It collects and preserves artifacts to implement the programs and conducts extensive research to ensure authenticity of the collections and presentation. Permanent and temporary exhibits are developed from the collections of the museum and from collections on loan from other museums, institutions, and individuals. Exhibits detail the development of the republic, immigration, social life, politics, military matters, agriculture, and commerce. After 1978 the museum enlarged and upgraded its collections to reflect all aspects of pre-1850 Texas. Its collection of 7,500 artifacts encompasses a representative sampling of early-nineteenth-century furniture and household furnishings, clothing and personal artifacts, firearms and armaments, agricultural and transportation implements, trade and professional tools, toys, books, prints, maps, and documents. A conservation lab was installed in 1979, and accession and conservation policies were written in 1980. Special education programs for school and other student and adult groups were begun in 1978. In 1982 more than 11,000 students participated in the scheduled programs. A quarterly newsletter, Washington-on-the-Brazos, was first issued in 1976. The publication was renamed Notes and reached 2,700 subscribers in 1993. Historical leaflets, brochures, exhibit catalogs, and other publications are produced by the museum. Packets and materials are available for teachers and schools. Audiovisual programs offer visitor orientation. The museum has participated in local festivals with pioneer craft demonstrations since 1978. In the late 1980s it started Pioneer Day Camp, which enables children to experience pioneer life. The museum holds an annual Texas Independence Day celebration in conjunction with Washington-on-the-Brazos State Historical Park and the Washington-on-the-Brazos State Park Association. Past exhibits at the museum have included a Texas natural history exhibit in 1990, an exhibit entitled "Sorrow whispers in the Wind": Native Americans and the Republic in 1992, and, in 1993, The Texas of Stephen F. Austin and Sam Houston, an exhibit that commemorated the 200th birthdays of these two Texans. The museum also maintains a research library of 3,000 works on Texas history, museum administration, and artifact identification.
In June 1992 the museum's new Collection Storage and Research Annex was completed. It provides 2,000 square feet of storage space and houses a conservation laboratory, a darkroom, a paint room, a woodworking shop, and two curatorial offices. That same year the museum received the Mitchell A. Wilder Silver Certificate Award from the Texas Association of Museums, given for the museum's book. The museum is funded primarily by state appropriations, with additional income from shop sales and program grants. It is a member of the Texas Association of Museums, the American Association of Museums, and the American Association for State and Local History. More than 68,000 persons visited the Star of the Republic Museum in 1993. The museum received accreditation by the American Alliance of Museums in 1972 and was re-accredited in 2010.
In 1998 the museum launched a plan to completely replace all of its exhibits and raised more than one million dollars for that effort. The new exhibits on the first floor opened in October 2000, and the second floor exhibition followed in March 2002. Star of the Republic Museum also began an extensive process of the digitization of its collection in partnership with the University of North Texas’s Portal to Texas History online site and completed the project, involving more than 9,000 images, in 2007. In 2016 the museum renovated its Discovery Room into the new Pioneer Playroom to enhance the learning experience for children. Operational control of Washington-on-the-Brazos State Historic Site was officially transferred from the Texas Parks and Wildlife Department to the Texas Historical Commission by the Eighty-sixth Texas Legislature, effective September 1, 2019. Management of the Star of the Republic Museum was transferred to the Texas Historical Commission on January 1, 2020.