Self-efficacy is a universal construct, but few validated measures exist for researchers in developing countries to use in assessing youths' perceptions of their ability to achieve academic success. This study examined the cross-cultural suitability and psychometric properties of an academic self-efficacy scale (ASES) adapted for the Ghanaian context. ASES construct validity was assessed with a sample of 4,289 Ghanaian junior high-school students and exploratory and confirmatory factor analysis. Invariance testing assessed the scale's measurement equivalence by gender and temporal stability of gender equivalence. The ASES is a valid, reliable one-dimensional scale for assessing young Ghanaians' perceptions of their academic capabilities, and it works equally well across genders. As adapted, ASES is a valid scale with utility for researchers examining predictors and effects of academic self-efficacy. The ASES has important implications for decisions regarding investment in programs aimed at improving academic self-efficacy of youth, both in sub-Saharan Africa and the increasingly diverse American public schools.