Practitioners are increasingly expected to provide reading instruction to students with cognitive disabilities to help them become literate. Whereas a phonics-based approach to reading instruction is regarded as a "best practice" for most young children, its effectiveness for children with cognitive disabilities is unclear. The purpose of this study was to explore this issue for a sample of 24 children with Down syndrome (DS) between the ages of 7 and 16 years and to model individual children's reading growth to identify specific child characteristics predictive of this growth. Results indicate that a majority of children demonstrated statistically significant growth in letter sounds, and reading of taught sight words and decodable words. Children with DS who entered the study with more advanced word identification skills made greater gains in decodable word reading; those with more advanced phoneme segmentation skills made greater gains in nonsense word reading. Overall, findings support inclusion of phonics-based reading instruction into academic programs for children with DS. [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.]