This paper seeks to establish the importance of targeted advertising in media markets. Using zip-code level circulation for U.S. newspapers, I show that newspapers facing more competition have lower circulation prices but higher advertising prices than similar newspapers facing little or no competition. I explain this by showing that newspapers in more competitive markets are better able to segment readers according to their location and demographics. This leads to greater homogeneity in the characteristics of subscribers and raises advertisers' willingness to pay for such readers. The results imply a substantial benefit to advertisers and media firms from targeted advertising.