The purpose of this research is to describe and understand the ways in which deaf middle school students understood and solved compare word problems, and to examine their overall strategy use in learning mathematics. The participants in the study were deaf middle school students, attending a residential state school for the deaf. Most of them used sign language as their primary language and who had different communication modes and learning styles. This study used grounded theory to shape its methodological framework. Data were collected using four methods. 1) A think-aloud technique was utilized in order to explore the complex cognitive processes of solving word problems. 2) Interviews were conducted using a structured questionnaire, to determine deaf students' use of self-regulation learning strategy. 3) A computation test was administered to assess the students' computation abilities, which are necessarily related to word problem solving. 4) Student background surveys were administered to examine their primary language environments at home. The think-aloud protocols were video recorded, then transcribed and analyzed using a constant comparative method. Four problem-solving behaviors were found in this study. First, deaf students have more difficulty understanding inconsistent language (IL) problems than consistent language (CL) problems. That is, they committed reversal errors on IL problems more frequently than on CL problems. These reversal errors resulted from their lack of syntax knowledge, lack of ability to make inferences from the problem details, lack of fractional knowledge, and use of key word strategy. Second, the students tended to use key word strategy, which is identified as a direct-translation approach (DTA), as they read and solved word problems, regardless of the problem type. Unlike hearing students in previous studies, most deaf students used a meaning-based approach (MBA) with easier problems and a DTA approach with complex problems. Third, the students' insufficient fraction knowledge contributed to their difficulties with word problems. Fourth, students' problem-solving behaviors varied depending not only on the complexity of problems and their prior knowledge about specific ideas, but also on their language mode, communication styles, and the amount of relevant knowledge they possessed. Finally, with regard to strategy use, the students tend to rely on asking their teachers for help when they encountered difficulties with mathematics, rather than trying to solve the problems themselves using a cognitive or metacognitive strategy. These participants should therefore be given opportunities to learn the cognitive and metacognitive strategies necessary to become independent learners, and to enhance their academic achievement in reading and mathematics. Overall, this study contributes to understanding why deaf middle school students have difficulty with word problems. The major finding is that the deaf students in this study do not have many opportunities to experience a variety of problem structures in their classes. Accordingly, in order to enhance deaf students' word problem-solving ability, these findings suggest that teachers should understand and address the students' characteristics, and provide more challenging problems with a variety methods of representing the problems. [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/en-US/products/dissertations/individuals.shtml.]