Students who are self-regulated leaners have been reported to perform more successfully in higher education institutions (HEIs). Therefore, instruments that can monitor students' motivation and learning have been devised and implemented. The aims of this work were to investigate the dimensionality of the motivated strategies for learning questionnaire (MSLQ) and compare the validation of the three competing models. Three competing measurement models (1-factor, 2-factor, and second-order factor) were selected as candidates. To reveal which model explained the original MSLQ most effectively and meaningfully, the original 15 indicators and 81 items were used, for which data was gathered from 945 participating engineering students in Thailand. The results of confirmatory factor analysis revealed that all three of the competing models fitted the data quite well, as all standardized factor loadings of these models were statistically significant. It appeared that two-factor and second-order factor models yielded a better overall fit to the data in comparison to one-factor model. These results confirmed that the original MSLQ is a reliable and valid measurement instrument, particularly the second-order factor model, which was the best model.