PROJECT SUMMARY Dyslexia and ADHD are prevalent neurodevelopmental disorders with a high rate of co-occurrence. Executive function (EF) challenges are common in both disorders, but research has yet to examine whether reading is impacted differentially by EF deficits or ADHD status. Dyslexia research is further limited by few longitudinal neuroimaging efforts examining reading growth and predictors of change in reading over time. Examining EF in dyslexia with ADHD and dyslexia without ADHD is an under-studied topic, despite the potential for clarifying etiological factors underlying reading difficulty and understanding the impact on academic outcomes that rely on reading. Scientifically, this effort is essential for disambiguating contributions of ADHD and EF to reading performance in dyslexia and testing associated theoretical models. Practically, this information is crucial for developing effective assessment approaches to understand reading difficulty and intervene effectively. Final datasets will include 80 typically developing readers (TD), 80 students with dyslexia, and 80 students with dyslexia and ADHD. Students will be recruited when they are in grade three or four (ages 8-10), and data collection will span three annual consecutive visits. The objectives are to: (1) precisely characterize ADHD status, EF skills, and reading skills; (2) examine behavioral and neurocognitive correlates of reading to differentiate contributions of EF deficits from ADHD status in dyslexia; and (3) determine whether behavioral and/or neurocognitive longitudinal reading growth for children with dyslexia differ by comorbid ADHD and/or EF deficit status. We predict that children with dyslexia will not differ based on reading measures when comparing children with comorbid ADHD versus dyslexia alone. We hypothesize that (1) among children with dyslexia (with and without ADHD), EF deficits - but not ADHD diagnosis - will be associated with worse reading performance and differences on neurocognitive indices of performance; (2) children with dyslexia who do not have EF deficits will demonstrate more reading growth than their peers with EF deficits, regardless of ADHD status, and (3) EF deficits will impact reading fluency but not reading accuracy performance and growth. Findings will inform us about whether any of these factors are related to children who make substantial progress in closing their reading gaps versus other children do not, as well as characterize the utility of EF measures/ADHD surveys in predicting reading growth among children with dyslexia. The significance of the research extends from discovery of etiology associated with reading difficulties to testing a theoretical model and constructing improved approaches to assessment and intervention for struggling readers. This proposal offers the largest and longest neurocognitive study of dyslexia to date. Most importantly, the current work offers the potential to discover whether EF or ADHD status may pr...