Some students still reach secondary level schooling without proficient foundational reading skills. Students who struggle to decode words accurately and efficiently will fail to adequately access grade-level texts independently, furthering the gap between themselves and their peers. Despite a subgroup of students reaching high school with word reading deficits, very few studies aimed at improving word reading/identification have been done with this age group. Phonics instruction has a rich research base for teaching children how to read. At the same time, research focusing on morphology may help address the unique needs of an older student demographic due to the prevalence of multisyllabic and morphologically complex words in grade-level texts. However, most reading intervention studies for secondary-age students focus on vocabulary and comprehension rather than decoding and word reading skills. The proposed research seeks to investigate the effectiveness of explicit morphology instruction (structural word analysis, syllable type instruction, and syllabication practice, and study of Latin bases and affixes) on the ability of 9th and 10th graders (N = 23) with decoding deficits to read morphologically complex words. Students identified with reading difficulties and registered for a special education reading intervention class received roughly 20 hours of intervention over 10 weeks. The gains in reading skills achieved by the treatment group in response to the intervention were compared to other students identified with reading deficits who did not participate in an intervention period. On measures of word reading and morphologically complex word reading, the experiment group performed better than the control group when controlling for performance at pretest, though without statistical significance. Hedge's "g" effect sizes for morphological knowledge (g = 0.97), word reading (g = 0.67), and complex word reading g = 0.60) suggest practical efficacy when compared to current literature. The results of this study provide important information needed to help inform how we address the instructional needs of students in high school struggling to read. Keywords: reading intervention, high school, decoding, word reading, morphology. [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.]