Emerging evidence suggests socioeconomic disadvantage may increase risk for eating disorders (EDs). However, there are very few studies on the association between disadvantage and EDs, and all have focused on individual-level risk factors (e.g., family income). Neighborhood disadvantage (i.e., elevated poverty and reduced resources in one's neighborhood) is associated with increased risk for anxiety/depression and poor physical health. To date, no studies have examined phenotypic associations between neighborhood disadvantage and disordered eating, or how any form of disadvantage may interact with genetic individual differences in risk for EDs. We examined phenotypic and etiologic associations between neighborhood disadvantage and disordered eating in 2,922 girls ages 8-17 from same-sex twin pairs recruited through the Michigan State University Twin Registry. Parents rated the twins on nine items assessing core disordered eating symptoms (e.g., weight preoccupation, binge eating), and neighborhood disadvantage was calculated from 17 indicators of contextual disadvantage (e.g., median home value, neighborhood unemployment). Puberty was measured using the Pubertal Development Scale to examine whether associations were consistent across development. At a phenotypic level, greater neighborhood disadvantage was associated with significantly greater disordered eating symptoms in girls at all stages of puberty (β = .07). Moreover, Genotype × Environment models showed that girls living in more disadvantaged neighborhoods exhibited stronger and earlier (i.e., during pre/early puberty) activation of genetic influences on disordered eating. Results highlight the critical importance of considering contextual disadvantage in research on etiology and risk for disordered eating, and the need for increased screening and treatment for EDs in disadvantaged youth. (PsycInfo Database Record (c) 2021 APA, all rights reserved).