This study attempts to explain the substantial differences in mathematical achievement of elementary students in a Delaware school district by analyzing the level of content and pedagogical knowledge of elementary math teachers. I examined tenth graders' longitudinal state test results in mathematics and found that performance in the primary years has a direct relationship on students' performance in mathematics in the secondary years (r = 0.86). I looked at several elementary teacher variables, such as teacher demographic data, content knowledge, and pedagogical beliefs about teaching mathematics and measured their impact on student scores. My analysis of 81 elementary teachers found that a teacher's level of content knowledge for teaching had the most direct impact on his/her students' achievement. The results revealed, however, that many elementary teachers lack this necessary knowledge to support student learning in mathematics. Many teachers struggle with mathematics and fail to develop appropriate instructional strategies to support struggling learners. Those teachers with a strong content knowledge for teaching tended to have higher student achievement (r = 0.614). To raise other students to these higher levels of achievement, I want to strengthen elementary teachers' proficiency and pedagogy in mathematics and recommend focused professional development, teacher collaboration, involvement of math coaches, and use of formative assessment in the classroom. [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.]