Since Block’s (2012) article, ‘Class and SLA: Making connections’, social class has received increased attention in applied linguistics research. This growing scholarship, however, yet is in need of a more robust theorization and rigorous methodological framework for investigating class-based research inquiries. This article thereby proposes Membership Categorization Analysis (MCA) as one possible approach for examining the participants’ endogenous makings of social class in situ. With interview excerpts of mothers discussing an English immersion policy proposal in South Korea, I will demonstrate how MCA can produce an analysis that is empirically grounded in the participants’ own categorial knowledge and commonsense reasoning about stratified social structure. Such an approach respecifies social class from being a rigid, abstract, and predetermined construct to a socially constructed category and accomplishment that is made relevant in the participants’ methods of practical action.