The popularity of the 1960s attire worn by 'Mad Men' characters such as Don Draper and Joan Holloway has led the 500-store chain to create style guides and window displays based around the show.
A competition will offer prizes including a walk-on part in a future episode.
Jack Calhoun, president of the Gap-owned chain, told The New York Times: "We're looking for unique ways to engage with our customers and 'Mad Men' totally fits with our aesthetic."
Before season three starts on August 16, there is a promotional push from Lionsgate Entertainment for the launch of season two on DVD on July 14.
As part of the push media agency Initiative has developed a partnership with showbusiness trade journal Variety.
This takes the form of a 'Mad Men' sponsored online display of Variety issues from the early 1960s.