Colleges and marketers are just starting to try to understand how to measure the success of their social-media efforts, says Mr. Stoner. Many are counting "touches"—the number of Twitter followers, the hits on a Web site, the number of friends or comments on a Facebook page. The more difficult question, he says, is, What do these measurements mean? Do tweets, blog posts, and Facebook "likes" translate into someone choosing your college, recommending it to a friend, attending an alumni event, or making a donation?