Mastery-approach (MAP) goals, focusing on developing competence and acquiring task mastery, are posited to be the most optimal, beneficial type of achievement goal for academic and life outcomes. Although there is meta-analytic evidence supporting this finding, such evidence does not allow us to conclude that the extant MAP goal findings generalize across cultures. Meta-analyses have often suffered from overrepresentation of Western, educated, industrialized, rich, and democratic (WEIRD) samples; reliance on bivariate correlations; and lack the ability to directly control individual-level background variables. To address these limitations, this study used nationally representative data from 77 countries/regions (N = 595,444 adolescents) to examine the relations of MAP goals to four antecedents (workmastery, competitiveness, fear of failure, fixed mindset) and 16 consequences (task-specific motivational, achievement-related, and well-being outcomes), and tested the cross-cultural generalizability of these relations. Results showed that MAP goals were: (a) grounded primarily in positive but not negative achievement motives/beliefs; (b) most strongly predictive of well-being outcomes, followed by adaptive motivation; (c) positively but consistently weakly associated with achievement-related outcomes, particularly for academic performance (β = .069); (d) negatively and weakly associated with maladaptive outcomes; and (e) uniquely predictive of various consequences, controlling for the antecedents and covariates. Further, the MAP goal predictions were generalizable across countries/regions for 13 of 16 consequences. While directions of effect sizes were slightly mixed for academic performance, perceived reading, and PISA test difficulty, the effect sizes were consistently small for most countries/regions. This generalizability points to quite strong cross-cultural support for the observed patterns.