In 1967, the King William Association was chartered as a non-profit corporation to preserve the oldest residential 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 Fair has grown from a one-block arts exhibit to a major Fiesta® San Antonio event. Through the efforts of hundreds of volunteers and thousands of Fairgoers, the Fair raises funds for arts, education, and community improvements.

The mission of the King William Fair is to support the arts, education, and community improvements with family fun in Texas' first residential historic neighborhood.