Empirical evidence from developed countries suggests that students' commitment to school is fundamental to their academic success. However, in developing countries, validated measures of student commitment to school do not exist. The current study helps fill this research gap by examining the validity and reliability of a commitment-to-school scale (CSS) adapted for the Ghanaian context. With a sample of 6,252 middle school-age students, the study employs exploratory and confirmatory factor analyses with weighted least squares means and variance adjusted (WLSMV) to establish and validate the construct as bidimensional. Measurement invariance tests confirm that the two-factor commitment model is generalizable across grade levels but not genders. Given its parsimony and good fit, the adapted CSS might be useful for future research in Ghana. Similarity of the model across grade levels suggests that the scale has potential uses in education research among diverse groups. We suggest that the CSS be developed further for better understanding of students' commitment to school.