Significance Although Americans believe the confusion caused by false news is extensive, relatively few indicate having seen or shared it—a discrepancy suggesting that members of the public may not only have a hard time identifying false news but fail to recognize their own deficiencies at doing so. If people incorrectly see themselves as highly skilled at identifying false news, they may unwittingly participate in its circulation. In this large-scale study, we show that not only is overconfidence extensive, but it is also linked to both self-reported and behavioral measures of false news website visits, engagement, and belief. Our results suggest that overconfidence may be a crucial factor for explaining how false and low-quality information spreads via social media.