The Museum was developed through the efforts of the McAllen Junior League to increase the quality of life for the citizens of the Rio Grande Valley, and to provide activities in the arts and sciences that are meaningful, educational, and available to the public. The Museum was chartered under the laws of the state of Texas on June 2, 1967 and granted its tax exemption certificate in August of that year. On October 7, 1968, the Junior League Museum Board entered into a leaning agreement with the City of McAllen for a 5,000 square foot building. Shortly after, a Board of Trustees was appointed and by-laws were adopted. The initial funding came from donations by local business firms, civic organizations, and individuals. An Executive Director was employed in June 1969, and building renovations were completed. The Museum was dedicated and formally opened to the public on October 26, 1969. On July 4, 1976, a new building was constructed and completed as a Bicentennial Project, and the Museum moved to 1900 Nolana, where it currently resides. A new building expansion, partially funded by the New Millennium Capital Campaign, was constructed and completed in 2001, which added an additional 17,259 square feet to accommodate 3 classrooms, an artist studio, cafe, gift shop, theater, and a hands-on exhibition space called the Children’s Discovery Pavilion. In the same year, the Museum completed its “Community Big Build” project and unveiled “RioScape: A Children’s Discovery Park”, incorporating play in an outdoor learning environment that reflects scientific and environmental concepts specific to the Rio Grande River. The Museum currently has over 50,000 square feet of exhibit space and public access areas.