PROJECT SUMMARY/ABSTRACT Children’s socioeconomic status (SES) is strongly associated with disparities in cognitive, linguistic, and academic development. Understanding the precise environmental and neurodevelopmental mechanisms that underlie these disparities is critical for developing maximally impactful interventions to reduce and ultimately ameliorate achievement gaps. This proposal will test an innovative developmental model in which specific features of children’s early language input engage the development of cascading frontotemporal neural networks that ultimately scaffold multiple aspects of social-cognitive development, including children’s language abilities as well as executive functioning and social cognition—critical school readiness skills that are known to contribute to SES achievement gaps in school. Two multimodal longitudinal studies will evaluate evidence for this hypothesis at multiple time scales, while also providing the candidate with crucial training to promote transition to research independence. Study 1 (K99 phase) will conduct novel analyses on existing data from a densely sampled longitudinal study of over 300 SES-diverse children across 10 years from preschool through late childhood/early adolescence. Aim 1 will investigate the role of specific features of early language input (linguistic vs. interactive) on SES differences in developmental trajectories of executive functioning and social cognition as they emerge across the preschool years (ages 3-5 years). Aim 2 will extend this investigation into long-term neurocognitive outcomes by evaluating whether early language input acts as a long-range mechanism influencing brain structure and functioning later in childhood that supports continued cognitive and social development, which may ultimately underlie SES disparities in academic achievement. Study 2 (R00 phase) will deepen the specific investigation of the dynamic development of these neurocognitive mechanisms in preschool through longitudinal study of a new cohort of children at ages 3 and 4 years. Aim 3 will specifically examine the influence of features of early language input on plasticity of interactive frontotemporal neural systems supporting linguistic, executive, and social cognition through preschool and the transition to Kindergarten. Results from both studies will help identify the precise components of early linguistic stimulation that drive development across multiple neurocognitive domains during a critical period of brain development, and determine the mechanisms by which exposures to specific social and environmental factors affect long-term neurodevelopment, neuroplasticity, and cognitive outcomes. Further, this work has direct translational implications to inform interventions that may help close and ultimately prevent income-achievement gaps and provide optimal neurodevelopmental outcomes for children from all backgrounds. This award will also provide the candidate, who has a strong background in ...