This journal club session will discuss “Estimating effects of hypothetical public health interventions on health disparities: A standardization-based simulation approach” (Wang et al., American Journal of Epidemiology, 2025). The article introduces a causal inference framework that moves beyond population-average effects to estimate how hypothetical interventions may reduce health disparities between social groups. Using longitudinal data from the Health and Retirement Study and the English Longitudinal Study of Ageing, the authors simulate interventions to reduce social isolation and loneliness and assess their impact on socioeconomic and racial disparities in cognitive functioning among older adults. We will hear directly from co-authors Xi Wang and Toshiaki Komura, who will discuss the motivation for the study, the proposed standardization-based simulation approach, and its implications for designing public health interventions.