PROJECT SUMMARY/ABSTRACT Reading disability (RD) is the most common neurodevelopmental disorder, affecting approximately 9% of children. Children with RD have significant difficulty with word reading and spelling despite typical cognitive ability. This disability is serious and can be life-long, impacting not only the ability to read and write (and learn from printed material), but also negatively influencing socio-emotional well-being. RD can be treated, and intensive research-based interventions often lead to significant improvements; however, there is significant variability in how children respond to intervention. A sizeable number of RD children (~30%) show minimal gains and are commonly referred to as non-responders. Identifying factors that predict response to intervention can help us understand why current interventions fail to meet the needs of all students and how to develop new interventions. However, such predictors remain poorly understood, particularly for older students. Extant knowledge of predictors at the individual and environmental level is limited because of a lack of large-scale research focusing on: (1) older children/persistently poor readers; (2) sensitive (including neurocognitive) measures collected in ecologically valid contexts; (3) school-based interventions and (4) frequent and equidistant assessment over the course of instruction. Here we propose a novel in-school cognitive neuroscience community engaged research (CER) approach that will afford frequent longitudinal assessment of children with RD as they undergo reading intervention as part of their school curriculum for two years. We propose to collect behavioral and neurobiological data from two cohorts of students with RD: the first cohort (n=204) attend private learning disability (LD) schools for children with reading difficulties that include intensive reading intervention at the core of their curriculum; the second cohort attend public and charter schools (n=204) with specialized curricula for students with RD. We also include a comparison sample of typically developing children (n=156) from public and charter schools to establish normative trajectories with our measures. Specific aims of the project are to: (1) Establish trajectories and predictors of reading gains in RD students at LD schools using standardized measures and information on school-based instruction; (2) Empirically test the predictive utility and trajectories of three theoretically motivated measures, guided by computational and neurobiological models of reading; (3) Assess the generalizability of our findings by adding a diverse sample of readers at public and charter schools; and (4) Investigate the multivariate relations between our behavioral, neural, and instructional measures from Aims 1-3 and reading growth across samples. This neurocognitive "field research" using in-school laboratories is a potentially transformative approach and an important step in understanding intervention respo...