Overview: Multisystemic Approach to Early Math Development and Math Learning Disability - Project Summary - Overall There is substantive variation in preschooler’s understanding of core number concepts (e.g., cardinality) and associated skills (e.g., counting; Geary & VanMarle 2016) that in turn is predictive of later individual differences readiness to learn formal math at school entry (Geary et al. 2018) and risk of math learning disabilities (LD; Chu et al. 2019). Child-centered interventions reduce these gaps (Dumas et al. 2019) but suffer from fade out and thus do not typically confer long-term benefits (Bailey, 2019). Similar fade out is found with individual therapy with young offenders, but sustained gains can be achieved with multisystemic interventions involving the child, home, and school (Henggeler et al. 2009), and it is time to consider this approach for LD and train the next generation of LD researchers to take a multisystemic perspective. The Research Core will provide a unique and much-need foundation for the development of multisystemic – including child, parents, home environment, and classroom – interventions for preschoolers who are at risk for long-term math difficulties, including math LD. The home component will provide the most thorough assessment ever conducted of the numeracy-related home environment, including assessment of parent’s math achievement and the complexity of the math-talk with their children, as related to preschoolers’ core number development (Zippert & Rittle-Johnson 2020). The classroom component will include teacher-report and direct observation of students’ engagement in learning opportunities and the complexity of the math presented in classrooms. The child-centered assessments will focus on the longitudinal development of the core number knowledge and skills that predict later school readiness for math learning and risk of math LD (Chu et al. 2019; Geary et al. 2018). This ambitious combination will enable the first-ever dynamic assessment of the multiple contextual and child-centered factors that contribute to children’s early math development, including factors that indicate risk of later math LD. The Leadership Core is seamlessly integrated with the Research Core to provide training and experiences in conducting child-, home-, and classroom-centered assessments, all organized around identifying the factors that influence the development of the core conceptual knowledge and skills that are the foundation for readiness for math learning at school entry and risk of later math LD (Chu et al., 2019; Geary et al., 2018). The PI and Co-Is have expertise in cognitive science, parent-child dynamics, public policy, and intervention research that in turn will provide a broad and unique mentoring experience for graduate students and a post-doctoral fellow. Mentees will also obtain valuable experiences with in-home assessments, classroom observations, and cognitive and achievement assessments and insights into how public policy decisions are influenced by basic research.