We demonstrate social contagion in attitudes and show it is more pervasive than believed. While prior research has demonstrated that individuals are influenced by others when explicitly exposed to others' attitudes, we demonstrate they are influenced even for issues where they were never explicitly exposed to group attitudes. In first two studies we show that individuals have a remarkable ability to predict the attitudes of others in a social group from very scant information--a phenomenon that we term `Social Clairvoyance.' Across three other studies, we delineate the psychological mechanisms that permit the performance of this feat - specifically, empathic responding directed at group members in an effort to understand their underlying motivations. Further, the empathetic simulation of others attitudes results in reaction in oneself towards the attitude object resulting in a shift in one's own attitudes. In three other studies, we show that the accurate prediction of others' attitudes results in a shifting of an individual's own attitude--a phenomenon we term `Attitudinal Contagion.' From this perspective, many marketing phenomena such as word-of-mouth, diffusion of new products, neighborhood effects may have been insufficiently understood since it does not require explicit exposure to the attitudes of another.