Literacy skills are fundamental for all learners. For students who require augmentative and alternative communication (AAC), strong literacy skills provide a gateway to generative communication, genuine social networking, improved access to academic opportunities, access to information technology and future employment opportunities. However, many teachers do not know how to design or implement appropriate evidence based literacy instruction for this population of students. Four dyads each consisting of one student with significant disabilities who required AAC and one instructional assistant participated in this study. The primary purpose of this single subject, multiple baseline across participants design study was to examine the effects of modified direct instruction on the number of opportunities to respond and correct academic responses during literacy instruction for students who require AAC. A secondary purpose of this investigation was to examine the effects of performance feedback provided to instructional assistants on opportunities to respond and correct academic responses during modified direct instruction. Furthermore, this study examined if modified direct instruction with performance feedback given to an instructional assistant would result in increased literacy skill acquisition for students with significant disabilities who require AAC. The Multi-Option Observation System for Experimental Studies, a real time data collection system, was used to collect data through the use of iPAQ handheld computers, and Flip MinoHd video cameras were used to record observations. Both technologies where used to provide performance feedback to participants. Although there were some limitations, the results demonstrated an increase in literacy skills for all participants. Furthermore, the implementation of modified direct instruction initially resulted in increased opportunities to respond and increased correct academic responses for all participants. These increases observed during the implementation of modified direct instruction did not sustain over time. However, with the implementation of performance feedback, opportunities and correct responses increased again and then maintained over a natural four week break in instruction. Implications from this study suggest that modified direct instruction with performance feedback provided to instructional assistants can be related to increased opportunities and correct responses during literacy instruction, as well as increased literacy skill attainment for students with significant disabilities who require AAC. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]