Testing measurement invariance across groups is essential for valid cross-cultural comparisons. This paper discusses the importance of measurement invariance in psychological research, particularly in cross-cultural studies. It outlines the theoretical and methodological aspects of measurement invariance within confirmatory factor analysis (CFA) and provides a step-by-step example of testing invariance using LISREL. The paper emphasizes that measurement invariance ensures that psychological constructs are measured consistently across different groups, allowing meaningful comparisons. It describes four levels of equivalence: functional, structural, metric, and scalar. The paper also discusses partial measurement invariance, which allows for comparisons even when full invariance is not achieved. It highlights the use of goodness-of-fit indices to assess model fit and provides a practical example using data from two groups of boys. The results show that the two-factor model of verbal ability supports measurement invariance across groups. The paper concludes that researchers should explicitly evaluate measurement invariance to ensure valid comparisons across cultural or group differences.Testing measurement invariance across groups is essential for valid cross-cultural comparisons. This paper discusses the importance of measurement invariance in psychological research, particularly in cross-cultural studies. It outlines the theoretical and methodological aspects of measurement invariance within confirmatory factor analysis (CFA) and provides a step-by-step example of testing invariance using LISREL. The paper emphasizes that measurement invariance ensures that psychological constructs are measured consistently across different groups, allowing meaningful comparisons. It describes four levels of equivalence: functional, structural, metric, and scalar. The paper also discusses partial measurement invariance, which allows for comparisons even when full invariance is not achieved. It highlights the use of goodness-of-fit indices to assess model fit and provides a practical example using data from two groups of boys. The results show that the two-factor model of verbal ability supports measurement invariance across groups. The paper concludes that researchers should explicitly evaluate measurement invariance to ensure valid comparisons across cultural or group differences.