Abstract Socioeconomic disadvantage and unhealthy lifestyles are both associated with greater physiological wear (allostatic load). Whether socioeconomic conditions modify the associations between health-related behaviors and allostatic load is unclear. We analyzed data from 24,187 US adults (National Health and Nutrition Examination Survey [NHANES] 2007–2018) and 17,507 Chinese adults (China Health and Retirement Longitudinal Study [CHARLS] 2011, extended follow-up to 2020).