["Applied Cognitive Psychology, Volume 40, Issue 3, May/June 2026. ", "\nABSTRACT\nThis research explored the relationship between overconfidence and conspiracy beliefs. In Study 1, cross‐sectional analyses demonstrated that both overconfidence in general knowledge and in climate change knowledge were positively associated with climate change conspiracy beliefs. In Study 2, we extended this approach to the COVID‐19 domain, assessing overconfidence in COVID‐19 knowledge and related conspiracy beliefs. An experimental manipulation of overconfidence did not provide evidence for a causal effect on conspiracy beliefs. Study 3 evaluated the reverse pathway by exposing participants to a conspiracy theory about the death of Jeffrey Epstein; this manipulation was not associated with increases in overconfidence. The exploratory post hoc moderation analyses, however, suggested that overconfidence may amplify the association between conspiracy exposure and conspiracy beliefs. Collectively, these findings are consistent with the interpretation that overconfidence is not directly responsible for the formation of conspiracy beliefs but may be linked to greater susceptibility to conspiratorial information.\n"]