In 1967, the King William Association was chartered as a non-profit corporation to preserve the oldest historic district in the state of Texas and to promote the unique cultural heritage of San Antonio. To further that mission, the Association hosted its first fair in 1968. Since then, the King William Fair has grown from a one-block arts exhibit to a major Fiesta event. Through the efforts of hundreds of volunteers and thousands of Fair-goers, the Fair raises funds for arts, education, and community improvements.

Admission to the festival is $5 for adults; for children twelve years and younger, admission is free.