This paper studies the economic effects of endorsements. In the publishing sector, endorsements are found to be a business stealing form of advertising that raises title level sales without expanding the market size. If anything, the endorsements decrease aggregate adult fiction sales. This might be a result of the endorsed books being more difficult than those that otherwise would have been purchased. Economically meaningful sales increases are also found for nonendorsed titles written by endorsed authors. This spillover demand demonstrates the broad range of benefits of advertising for firms operating in a multiproduct brand setting.