Today's math students must be able to problem-solve, reason, and communicate in math. That said, teachers on the elementary level must change their beliefs on how mathematics should be taught. Marzano (2003) stated that the classroom teacher is the single-most important factor in student learning. The second important factor in student learning is the principal, the instructional leader of the building. The decisions made by the principal can have a direct impact on mathematics instruction, which also impacts student achievement in mathematics. The present research focused on principals' leadership style on the elementary level in Grades 3-5 and the impact that leadership style has on ensuring that students on these levels have a strong mathematical foundation. The researcher designed an empirical study using a qualitative research method to investigate the leadership style of elementary principals and the impact of their leadership style on student achievement in mathematics. The researcher also investigated the math coaches' role and how their joint leadership with the principal's leadership style affects student achievement in mathematics in the elementary school. The data were gathered by the researcher from interviews with elementary math coaches and principals as well as documents from the New Jersey Department of Education. The findings revealed that principals must become instructional leaders and focus on teaching and learning. This leadership style will help principals better understand what it takes to improve student achievement in mathematics. Elementary principals must be part of all professional math development they offer at their schools or districts. Also, elementary schools can benefit from having a math coach work with the instructional leader and teachers to change instruction and improve student achievement in mathematics. [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.]