Doctoral thesisThis thesis reports the findings of the implementation of a designed Intervention Learning Materials for Improving English Language Comprehension Ability (ILMIECA) among students with Hearing Impairment (HI) in inclusive classroom through a Collaborative Instructional Approach (CIA). The ILMIECA were designed and developed within the framework of the Social Constructivism and Text Comprehension theories. Social Constructivism Theory was used in this study because of its emphasis on collaborative learning. In the context of this study, students with HI learn well in an inclusive setting when they are engaged with peers. The Text Comprehension Theory was deemed important in this study due to its emphasis on combining linguistic structures with the learners’ background knowledge and experience to enable readers to comprehend a text. Three main objectives guided this study: to analyse quality criteria for designing guidelines and specifications for the development of the ILMIECA based on the Collaborative Instructional Approach, to design, develop intervention materials through prototypes for improving English language comprehension ability of students with HI, and to evaluate the efficacy of the ILMIECA in improving English language comprehension ability among students with HI in inclusive classroom. The study was conducted at Kazima in Tabora Region, Bwiru Boys and Buhongwa Secondary Schools in Mwanza Region. The study adapted developmental design using pre-test post-test quasi experimental mixed approach. The quantitative evaluation employed paired sample t-test and independent t-test to compare scores within group; and between the experimental and control groups. The qualitative evaluation used phenomenographic approach. Thus, the study designed, developed, and evaluated ILMIECA with 7 reading comprehension lessons. Interview guides, observation, tests, and documentary review were employed in designing, developing, and evaluating the ILMIECA. The main findings obtained from interviews revealed that teachers and students were satisfied with impact of ILMIECA in improving comprehension skills among students with HI. Further, the post-test mean scores of the students in experimental group improved significantly in comparison with the control group. These results imply that the experimental group had high comprehension skills as compared to the control group. Hence, English language comprehension ability improved significantly in the part of experimental group.