Who Counts as a First-Generation Student? Definitional Accountability, Classification, and Institutional Practice in Higher Education

First-generation student status is widely used in higher education research and practice, yet operational definitions vary across studies and institutions. This critical conceptual and methodological review analyzes 56 empirical studies and draws on a targeted Scopus search that produced 412 deduplicated records for screening on definition, measurement, and classification. The analysis identifies differences in educational thresholds, family scope, attendance versus completion, and sources of classification. It advances definitional accountability as a minimum reporting expectation and proposes a framework linking classification rules to research purposes, institutional uses, and the consequences of inclusion or exclusion.