In England, students with immigrant background exhibit lower educational attainment than those without immigrant background. Family socioeconomic status (SES) helps explain differences in educational attainment, but a gap remains that differs in size for students with different immigrant backgrounds. While the explanatory repertoire for the remaining gap is broad, it has been neglected to comprehensively investigate whether family SES constructs are equivalent across students with different immigrant backgrounds. Using data from the first wave of the Children of Immigrants Longitudinal Survey in Four European Countries (CILS4EU) for England (n = 4,315), the paper applies exploratory structural equation modelling (ESEM) to evaluate measurement invariance of family background constructs across students without and with immigrant background, specifically Pakistani/Bangladeshi immigrant background. Results suggest differences in the structure of family SES indicators across groups and in their association with educational attainment. Complementary variables are suggested to enhance family SES indicators. Findings are relevant to researchers investigating educational inequalities related to immigrant background.