The Arizona Costume Institute was founded in 1966 to support Phoenix Art Museum's Fashion Design Department in the acquisition and preservation of garments and accessories of historical and aesthetic significance. It also promotes appreciation of fashion design through programs and support of the Museum's exhibitions.

Some activities include monthly fashion and textile programs, visits to private collections and studios, events at local fashion stores, travel, luncheons and receptions. Phoenix Art Museum's fashion design collection is one of only about 15 such collections housed in American art museums. ACI's support of this collection area depends on the enthusiasm of dedicated volunteers to help maintain and expand the collection.

Membership provides an opportunity to share with others your interest in fashion as art. Exhibitions that focus on clothing both as an art form and cultural phenomenon are rotated regularly in the Fashion Design Gallery. They underscore the significance of fashion as it relates to social and economic history. The Astaire Library of Costumes included in the Museum's Lemon Art Research Library houses many rare books and prints relating to costume and textiles.