Despite the tremendous resources devoted to marketing on Facebook, little is known about its actual effect on customers. Specifically, can Facebook page likes affect offline customer behavior, and if so, how? To answer these questions, the authors conduct a field experiment on acquired Facebook page likes and find them to have a positive causal effect on offline customer behavior. Importantly, these likes are found to be most effective when the Facebook page is used as a platform for firm-initiated promotional communications. No effect of acquired page likes is found when customers interact organically with the firm's page, but a significant effect is found when the firm pays to boost its page posts and thus uses its Facebook page as a platform for paid advertising. These results demonstrate the value of likes beyond Facebook activity itself and highlight the conditions under which acquiring likes is most valuable for firms.