This study investigates whether the emotional effects of music can be manipulated by social influence in an online music listening setting. More than 5000 participants listened to five randomly chosen music excerpts (of a total of 23 excerpts) and, after each one, rated induced emotions along arousal and valence dimensions. By providing different labels for the same information about the emotional effects of music, we were able to compare social influence with nonsocial informational influence. Accordingly, participants were confronted with four different rating conditions. In contrast to a control group (without feedback), two groups received feedback allegedly based on the ratings of preceding participants (social feedback), and one group received feedback allegedly based on a computational analysis of the excerpts (informational feedback). Instead of using real feedback from previous participants or computations, the feedback was manipulated, in that the upper or lower quartiles of a pretest rating were presented to the participants. Confirming predictions, results show that the manipulated feedback significantly influenced participants' ratings in groups with social feedback. Additionally, social feedback was more influential than informational, indicating that conformity might have been also based on a social and normative basis. We conclude that emotional effects of music might be socially influenced owing to normative and informational motivations to conform.