Reading teachers are faced with the challenge of providing instruction to a population of diverse students with various abilities and styles of learning within local and state school districts. In an effort to improve student performance on high-stake examinations in reading, teachers continue to seek the most effective instructional strategies. Accordingly, the theoretical framework of this study was based on the philosophy of differentiated instruction. This sequential mixed-methods study examined teacher perceptions of reading instruction as well as the effects of differentiated instruction and other instructional strategies on student achievement in reading in a primary school. The questions in this study were designed to examine teacher perceptions of differentiated instruction and other instructional strategies used in reading. Qualitative data, in the form of observations and interviews, were collected from a convenience sample of second-grade teachers. The data was coded in order to identify various themes and trends. Observation and interview data revealed that teachers tended to use instructional approaches that produced satisfactory results on the CRCT. The quantitative hypothesis concerned using independent samples t-test to determine if there was a significant difference between the performance of students taught in a differentiated classroom and those taught in a traditional class. The OAS benchmark results indicated that the reading comprehension of students in the differentiated classroom was significantly higher than the students in the traditional classroom. The implications for positive social change are providing teachers, educational leaders, and professional development facilitators with information on differentiated instruction that can help increase the performance level of all students in reading. [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.]