This article summarizes the key finding of a study that (a) tests the measurement invariance (MI) of the popular Students' Approaches to Learning instrument (Programme for International Student Assessment [PISA]) across ethnic/cultural groups within a country and (b) discusses implications for research focusing on the role of affective measures in immigrant and minority education. The Students' Approaches to Learning instrument captures some of the most prominent constructs in educational psychology. Results indicate significant variation in MI across various affective scales and across cultural groups. This study demonstrates that even if MI for specific scales is established across countries, it is still necessary to test MI across cultural groups within a country. We then discuss implications of MI across immigrant groups and highlight the relevance of MI testing for all research studying the affective conditions of educational achievement among immigrant students or the educational motivation of minority students. (Contains 6 tables and 3 notes.)