Recently, researchers have paid more attention to the aspects of classroom learning environments because of their effects on students' cognitive and effective outcomes. However, current literature reveals the lack of research that explores the factors of classroom environments in Vietnamese context. The present study, therefore, aims to validate the psychometric properties of the 25-items version of the My Class Inventory (MCI), translated into Vietnamese for 487 secondary school students. Factorial analysis showed an acceptable fit for the four-factors structure of the MCI -- cohesiveness, competitiveness, satisfaction, and friction -- to be appropriate for secondary school students. Internal consistency reliabilities of the general scales and four subscales were satisfactory. Results support the suitability of the MCI to assess students' classroom environment within Vietnam's educational context. The study recommended, among other things, that future studies should be conducted to explore the validity of the MCI on other samples of Vietnamese secondary students.