How does a firm's advertising decision depend on how much its competitors spend? Does a firm's advertisement induce consumers to learn about the entire product category, benefiting the competitors? We study these questions in the context of the U.S. craft brewing industry and analyze how advertising spillovers from competitors shape a firm's advertising strategy. By leveraging the discontinuity in advertising across market borders, we find that firms spend less on advertising when facing more competitors, suggesting that advertising spillovers exist. We estimate that advertising spillovers are more pronounced in markets hosting a larger number of craft breweries, as the increase in advertising spending in response to rivals' advertising is smaller in these markets. We also find the elasticity estimates to be smaller for the time periods after the Brewers Association launched a generic advertising campaign, which likely increased consumer awareness of craft beer products. We discuss these findings using a simple limited information discrete choice model of consumer demand, incorporating both persuasive and informative advertising approaches, and analyze the competitive landscape of the craft beer market.