<b>Background:</b> Previous research shows that socioeconomic status (SES) positively impacts children's development, yet the benefits are not equally distributed across racial groups. According to the Minorities’ Diminished Returns (MDRs) framework, Black children tend to experience smaller gains from parental education compared to White children. <b>Objective:</b> Building on the MDRs framework, this study examines whether high financial strain contributes to the diminished returns of parental education for Black children, using data from the Adolescent Brain Cognitive Development (ABCD) Study. We hypothesized that: (1) there would be a positive effect of parental education on total cortical volume, (2) this effect would be weaker for Black than White children, and (3) higher household financial strain in Black families would mediate the diminished returns of parental education on total cortical volume for Black children. <b>Methods:</b> Data were drawn from the baseline ABCD Study, focusing on 7,936 9- and 10-year-old children identified as either Black (n = 1,775) or White (n = 6,161). Parental education was the key independent variable, covariates included age, sex, household income, and marital status, race was the moderator, financial strain was the mediator, and total cortical volume was the outcome. Structural Equation Models (SEMs) were employed to examine the associations between parental education and cortical volume, with financial strain as a mediator and race as a moderator. <b>Results:</b> Higher parental education was associated with greater cortical volume in the pooled sample. However, this effect was significantly weaker for Black children. Financial strain partially mediated the observed diminished returns of parental education. <b>Conclusion:</b> High financial strain experienced by middle-class Black families partially explains why the association between parental education and child development is weaker in Black than White families. Interventions aimed at enhancing educational quality, increasing employability, expanding access to higher-paying jobs, and reducing labor market discrimination against Black individuals may help address racial inequities in child development in the U.S. Efforts to reduce financial strain should extend beyond low-income populations to also support higher-educated minority families.
