Background: Low cardiovascular health (CVH) in childhood is linked to risk of cardiovascular events in adulthood in the US. Relationships between neighborhood characteristics could be important for CVH in children, as appears to be the case in adults. We sought to assess such associations, representing neighborhood characteristics by the Child Opportunity Index (COI) and using a composite behavioral CVH score in youth. Methods: We used baseline data from the Young Hearts study, which is studying CVH trajectories of children ages 0-20. We linked children’s addresses to the COI, with domains encompassing: (1) social and economic, (2) health and environmental, and (3) educational opportunity. CVH behaviors were defined using the Life’s Essential 8 framework and included: self-reported diet, physical activity, nicotine exposure, and sleep. Linear regression models assessed the association between COI and overall and component behavioral CVH scores after adjustment for child demographics, family SES, and moves in the last year. Overall CVH scores comprised of the mean value of 4 behavior-specific scores (each 0-100 points). Results: Participants (N=2202) were 9.5±5.4 years old; 46.3% were female, and 47.05% identified as non-Hispanic White, 25.3% as Hispanic, and 17.9% as non-Hispanic Black. Compared with high (favorable) COI, individuals with low COI had a 2.15-point lower (worse) mean behavioral CVH score (p=0.003); however, those with moderate COI did not have significantly lower mean scores. The pattern for the education domain was similar but weaker. In the social and economic domain, those with low and moderate COI both had lower behavioral CVH scores than those with high COI. The health and environment domain was not independently associated with CVH. Of individual metrics, only sleep scores (beta=68.32, p=0.005) were independently associated with COI after adjustment. Conclusion: COI, especially social and economic factors, were associated with overall behavioral CVH among a diverse population of children.