This study examined whether the five scales of the MUSIC Model of Academic Motivation Inventory produced valid scores when used in university English language courses across four different countries. We surveyed 1,147 students in English language courses in Iran, Mexico, China, and Egypt and analyzed their responses by performing measurement invariance testing using multiple group confirmatory factor analysis. The internal consistency reliability of the five MUSIC Inventory scales was acceptable. The configural, metric, and scalar invariance held across the four countries, providing evidence of construct validity for the five scales. Relationships between the MUSIC Inventory scales and measures of behavioral engagement, disaffection, and achievement provided some evidence of criterion validity, but some inconsistencies with expected relationships were noted. Overall, this study provides validity evidence for using the inventory in English language courses.