Some aspects of human metacognition, such as the ability to consciously evaluate our beliefs and decisions, are hypothesized to be culturally acquired. However, direct evidence for this claim is lacking. As an initial step toward answering this question, here we examine differences in metacognitive performance between populations matched for occupation (students), income, demographics and general intelligence but drawn from 2 distinct cultural milieus (Beijing, China and London, U.K.). Chinese participants showed more efficient metacognitive evaluation of perceptual decision-making task performance compared to U.K. participants. These differences manifested in boosts to postdecisional processing following error trials, despite no differences in first-order performance. In a second experiment, we directly replicate these findings and show that a metacognitive advantage generalizes to a task that replaces postdecision evidence with equivalent social advice. Together, our results are consistent with a proposal that metacognitive capacity is shaped via sociocultural interactions. (PsycInfo Database Record (c) 2022 APA, all rights reserved).