Considerable academic attention has been placed on analysing whether, and to what extent, socioeconomic background affects higher education participation. However, the use of socioeconomic status (SES) is problematic as it may be constructed from various data sources. Similar issues can be inherent in study design-related operationalisation decisions. This paper proposes a meta-method analysis to deconstruct the concept of SES and to investigate the study designs in 31 studies reporting on socioeconomic inequalities in Finland and New Zealand. The paper highlights the key operationalisation decisions undertaken and the diversity of methodological approaches, calling into question the within- and cross-country comparability of the findings. The review also produces an improved understanding of limitations and strengths of the existing knowledge based in the two case countries and suggests avenues for further research.