Children tend to overestimate their performance on a variety of tasks and activities. The present meta-analysis examines the specificity of this phenomenon across age, tasks, and more than five decades of historical time (1968-2021). Self-overestimation was operationalized as the ratio between children's prospective self-estimates of task performance and their actual (i.e., objectively measured) task performance. A total of 246 effect sizes from 43 published articles were analyzed (4277 participants; 49.6% girls; sample mean ages range from 4 to 12; 86.0% of studies conducted in North America or Europe). Children's self-overestimation was robust across tasks, with their estimates of performance being 1.3 times their actual performance. In addition, children's self-overestimation decreased with sample age and increased with the year of data collection.