Viral marketing has generated a lot of excitement recently, in part because it seems like the ultimate free lunch: Pick some small number of people to seed your idea, product, or message; get it to go viral; and then watch while it spreads effortlessly to reach millions. Unfortunately, for every high-profile example of a successful viral product—FlashMobs, the Star Wars Kid, or JibJab’s 2004 election spoof—there are many more attempts that fail. Reliably designing messages to exhibit viral properties is extremely difficult, it turns out, as is predicting which particular individuals will be responsible for spreading them. (See Duncan Watts’s February 2007 HBR List item, “The Accidental Influentials.”)
A version of this article appeared in the May 2007 issue of Harvard Business Review.
