This study examined the factor structure and longitudinal measurement invariance of the Learning and Study Strategies Inventory (LASSI) through the application of exploratory and confirmatory factor analyses to data from two samples of university students from Hong Kong. The first sample consisted of Mainland Chinese students who completed the LASSI twice over a 12 month period, while the second sample consisted entirely of local Hong Kong students who completed the LASSI twice over a 15 month period. Results indicated that the empirically derived four-factor model showed a much better fit than the originally proposed three-factor model. For both samples, the four-factor model was partial strong invariant (equality of factor structure and factor loadings for all scales, equality of intercepts for several scales) with moderate stability coefficients across time. These results demonstrated that the LASSI had adequate invariance properties for use as a longitudinal assessment tool of student study behavior.