ADHD is a behavioral cognitive correlate of achievement associated with lower reading performance. The externalizing and internalizing symptoms that characterize ADHD behaviors negatively impact the engagement of students experiencing reading difficulties and the ability to regulate attention and behavior during the reading acquisition process. There is also considerable comorbidity between ADHD and reading-related learning disabilities driven by genetic and environmental pathways. This poses challenges for interventions (i.e., an environmental factor) containing reading instruction designed to improve the reading performance of children who may be exhibiting ADHD behaviors. This study examined the associations between ADHD behaviors and response to reading instruction, using a diverse sample of at-risk kindergarten and first-grade children (N = 715) across 67 classrooms who participated in a randomized control trial evaluating the Individualized Student Instruction (ISI) reading intervention. A structural equation modeling approach assessed teacher-rated ADHD behaviors predicting response to instruction across several teacher-implemented instructional reading approaches (ISI vs. BAU). Qualitative differences in the associations based on the operationalization of ADHD behaviors (i.e., inattention, hyperactivity-impulsivity, and combined) were examined. Exploratory analyses were performed to examine whether the association between ADHD behaviors and children's response to reading instruction significantly differed by instructional group. Several subscales of the SWAN Rating scale measured ADHD behaviors. Response to instruction was based on residual gain scores in reading-related skills measured as a composite of decoding and expressive vocabulary skills from subtests of the Woodcock-Johnson III Tests of Achievement. A statistically significant negative relation was found between the ADHD behaviors and response to instruction. Higher teacher-rated ADHD behaviors predicted lower SDs in response to reading instruction. Qualitatively, the combined ADHD behaviors produced the strongest association and explained the most variance than the other ADHD behaviors. Exploratory analyses suggested that there were significant instructional group differences for inattention and hyperactivity-impulsivity but not the combined ADHD behaviors. The multiple-group models favored the ISI group. ADHD behaviors and response to instruction were more strongly related to lower responsiveness to instruction in the BAU group compared to ISI. This study highlights the role of distinct ADHD behaviors in early reading-related skills in response to reading instruction. These preliminary analyses have implications for classroom-based reading instructional practices and empirically replicating evidence to understand the influence of ADHD behaviors on efforts to remediate poor reading in children. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]