There is emerging interest in the relationship between residential and school segregation and racial and ethnic health disparities. Much of the current research looks at physical health outcomes, health behaviors, and healthcare access. However, The relationship between residential and school segregation and mental health is still understudied. This study explores this relationship and tackles the long-term effects of residential and school segregation in midlife. The relationship is explored using data from the High School and Beyond study (1980) and subsequent midlife follow-ups (2014-2015 and 2021). This study uses information on race and ethnicity, where study participants went to school, and participants’ self-reported mental health diagnoses later on at midlife. The findings of this study will allow future research to identify what theoretical models and methodological strategies can best evaluate a possible long- term causal relationship between residential/school segregation and mental health.