Social networking sites (SNSs) provide users with an efficient interface for distributing information, such as photos or wall posts, to many others simultaneously. We demonstrated experimentally that this type of indiscriminate one-to-many (i.e., monologue) communication may induce self-focused attention and thereby impair perspective taking. The present study used multiple paradigms to explore the link between engaging in online one-to-many communication and a decrease in perspective taking. Experiment 1 revealed that Facebookers who published a personal photo to the public or their friends were less likely to adopt another person’s visual perspective than were those in the control group. Experiment 2 showed that Facebookers who engaged in indiscriminate one-to-many wall posting were more likely than those in the control group to rely heavily on their own perspectives. A state of self-focus, as measured by greater Stroop interference in naming the color of self-relevant versus neutral words, mediated the detrimental effect of indiscriminate one-to-many communication on cognitive perspective taking. These findings suggest that indiscriminate one-to-many communication on SNSs may promote public self-focus, leading to self-referential processing when making social judgments. Online monologue communication may be more harmful to perspective taking than previously understood.