The term “bandwagon effect” denotes a phenomenon of public opinion impinging upon itself: In their political preferences and positions people tend to join what they perceive to be existing or expected majorities or dominant positions in society. It has been most intensely discussed with regard to elections and issue attitudes. Only in recent years have carefully designed studies succeeded in demonstrating that bandwagon effects really exist. However, the observed bandwagon effects have usually been rather weak, and contingent on specific conditions.