Metacognition is defined as a higher-order thinking skill that enables individuals to monitor, control, and regulate their thinking and behavior. In education, this skill is important, as learners need to self-regulate their learning behaviors for successful lifelong learning. Thus, it is essential for educators and learners alike to know their metacognitive skills. Researchers can assist in this endeavor by developing sound and valid quantitative measures for psychological phenomena such as metacognition. No measure is more commonly used for this purpose than the Metacognitive Awareness Inventory (MAI). In the present study, the International Group on Metacognition validated the MAI employing a standard, international Spanish with a robust sample of 12 Spanish-speaking countries and 1,622 undergraduate university students. Results revealed a solid final baseline confirmatory factor analysis model for all 12 countries that supports the original two-factor structure reported in English-speaking samples from the United States. Additionally, multigroup measurement invariance analyses revealed that although five parameters varied slightly across some countries, chi-square difference tests indicated that the comparison model with these constraints freely estimated was not significantly better than the fully constrained null model, supporting measurement invariance across countries. Thus, our version of the MAI using standard, international Spanish is a valid and reliable tool for measuring metacognitive awareness in Spanish-speaking countries.