Across 6 studies we investigated the development of overconfidence among beginners. In 4 of the studies, participants completed multicue probabilistic learning tasks (e.g., learning to diagnose “zombie diseases” from physical symptoms). Although beginners did not start out overconfident in their judgments, they rapidly surged to a “beginner’s bubble” of overconfidence. This bubble was traced to exuberant and error-filled theorizing about how to approach the task formed after just a few learning experiences. Later trials challenged and refined those theories, leading to a temporary leveling off of confidence while performance incrementally improved, although confidence began to rise again after this pause. In 2 additional studies we found a real-world echo of this pattern of overconfidence across the life course. Self-ratings of financial literacy surged among young adults, then leveled off among older respondents until late adulthood, where it begins to rise again, with actual financial knowledge all the while rising more slowly, consistently, and incrementally throughout adulthood. Hence, when it comes to overconfident judgment, a little learning does appear to be a dangerous thing. Although beginners start with humble self-perceptions, with just a little experience their confidence races ahead of their actual performance.