Conspiracy theories have a become a topic of much concern given their involvement in political violence and other recent events. But what do we know about these things we call “conspiracy theories”? Are beliefs in them increasing? Are conspiracy theories driving deleterious political and medical behaviors? Who is to blame for the salience of conspiracy theories in our politics and what should we do about it? In this talk, Professor Uscinski will draw on a decade of American and European polling data to answer these and other questions about conspiracy theories.