Overconfidence plays a role in a large number of individual decision biases and has been considered a “meta-bias” for this reason. However, since overconfidence is measured behaviorally with respect to particular tasks (in which performance varies across individuals), it is unclear if people genuinely vary in terms of their general overconfidence (i.e., unconfounded by task performance). We investigated this issue using a novel measure: The Generalized Overconfidence Task (GOT). The GOT is a difficult perception test that ask participants to identify objects in fuzzy (“adversarial”) images. Critically, participants’ estimated performance on the task is not related to their actual performance. Instead, variation in estimated performance, we argue, arise from generalized overconfidence: i.e., people indicating a cognitive skill for which they have no basis. In a series of studies (total N = 1,052), the GOT displayed strong convergent and divergent validity (Studies 1a and 1b), along with superior reliability in a test- retest design (Study 2) when compared to the other overconfidence measures. Indeed, the GOT is a strong predictor of a host of behavioral outcomes, including conspiracy beliefs, bullshit receptivity, overclaiming, and the ability to discern news headlines, indicating that generalized overconfidence may, in fact, be a genuine individual difference.