The results of an experiment that examined the influence of ad format on memory structure for the brand are presented.Mysteryads (i.e., those in which the brand is not identified until the end of the ad) were found to be more effective in building associations in memory between the product category and the brand than identical ads in which the brand was identified early in the ad. These mystery ads were most effective for novel brands, with which viewers were unfamiliar. A possible mechanism for the process is described, and implications of strong category–brand associations for brand choice are discussed.