PROJECT SUMMARY Household socioeconomic status (SES) is a major contributor to child brain and cognitive growth, and related to their future educational and occupational outcomes. Lower-SES adversities hinder children's executive functions (EF) and language, which impede their classroom performance. Lower-SES children also have lower literacy and language due to impoverished home literacy and language environment (HLE). Lower SES and HLE exacerbate children's classroom difficulties. Yet, despite lower-SES disadvantages, some families are attuned to and foster their children's academic goals and actively enrich HLE. When lower-SES families have access to HLE enrichment programs, such experiences can scaffold gains in literacy and language outcomes. That is, enriched HLE mitigates the adverse impacts of lower SES on child development. Given the critical role of early cognitive skills in classroom performance, understanding the ways household SES versus HLE affects child development, especially brain growth, provides key implications for policymaking and interventions. Lower SES negatively impacts brain structure and function, centrally within the brain networks that support EF and language. After accounting for SES effect, recent studies report that HLE taps brain networks linked to literacy and language, suggesting a protective mechanism. Interestingly, our preliminary results revealed that HLE also overlaps with SES in explaining differences in brain regions subserving EF. Given the role of EF in reading and language, this suggests a potential additive mechanism. But, these studies focus exclusively on how frequently parents and children read together, which thereby narrows the multifaceted nature of HLE. To unpack child socioeconomic circumstances, we examine how brain networks link to specific dimensions of a multifaceted HLE (m-HLE). We drew upon prior behavioral literature, and compiled a comprehensive measure for m-HLE. Not only do we account for child-initiated HLE, we also capture the quantity and quality of parent-initiated HLE. We hypothesize that the ways dimensions of m-HLE interact with different brain networks contribute to mediate and/or moderate the impact of SES on child outcomes. Our first aim focuses on how m- HLE versus SES affect brain, and in turn child outcomes. While SES will predict brain regions subserving EF and language, we anticipate that m-HLE will contribute to brain regions that support language and literacy. Though parents are not always available, such that children likely recruit self-regulation and voluntarily initiate HLE, which may also tap EF brain regions. Our second aim examines whether and how m-HLE interacts with the brain to mitigate lower-SES adversity. We speculate that, despite lower SES, children with enriched m-HLE will exhibit similar interaction between brain networks as their higher-SES peers to scaffold positive outcomes. Results from this proposal will fill critical gaps in understanding how...