Surveillance efforts and research are needed to better understand the trends in aging and associated disparities in SES and healthcare access worldwide, especially in light of the seemingly paradoxical findings in the recent literature. However, measurement issues complicate our ability to fully understand the relationship between SES and healthcare access among older adults. In the field of health services research, SES is not uniformly measured, which has vast implications for advancing healthy aging. Measurement of SES in health services research is difficult, due to the variety of definitions and constructs measured under this concept (–). Choice of definition and measurement affects the outcomes of disparity research. Considering the complexity of appropriately measuring SES (a combination of education, employment, and income), multidimensional SES measures (i.e., household income vs. community wealth) may create a more accurate picture of the drivers of health disparities (, ). Unfortunately, many studies simply measure and utilize one aspect of SES (e.g., household income), which does not fully encapsulate SES and only serves as a proxy to the theorized construct. Or, studies include multiple measures of SES, but include them in statistical models as separate variables, not accounting for multicollinearity and interdependence. This measurement issue is further complicated when measuring SES in later life because of the complexities of SES based on educational norms of decades past, years post-retirement, and subsidized healthcare in advanced age. As such, it is suggested that SES is better measured by wealth instead of income as people age and retire (). This ultimately has practical implications that influence the associated findings, interpretations, and recommendations for action to improve healthcare access within the field. For example, while increasing health insurance coverage resulted in improved access to care in China, income-related disparities still existed. Higher-income older adults accessed more outpatient services (). This suggests a need to further explore the relationship between income, health insurance, and healthcare access among older adults. Developing standardized and evidence-based guidelines for trend surveillance among these factors would allow more accurate and consistent comparisons between countries and other contexts. Likewise, creating expert consensus on measurement issues related to SES is necessary to improve our understanding of the relationship between SES, access to care, and healthy aging, and facilitate moving beyond mortality as the major outcome of that relationship., Keywords: socioeconomic status, healthcare access, access to care, healthy aging, older adults Introduction Healthy aging, also known as successful aging (1), is defined by the World Health Organization as “the process of developing and maintaining functional ability that enables well-being in older age” (2)., Healthcare patients of lower socioeconomic status (SES) are affected by such disparities through lesser quality and accessibility of healthcare services. SES is defined by the American Psychological Association as the social standing or class of an individual or group, often measured through the intersection of education, income, and occupation..