Math instruction has undergone a tremendous amount of change since the late 1950s. "New math" of the 1960s, the standards movement, back to the basics in the early 90s, and now the common core standards have all had an impact on how mathematics is taught. This study examined the Math Expressions program, a conceptually based program implemented in the district of this study's elementary schools, and the impact this program has had on students' mathematical proficiency and growth based on scores from the North Carolina End-of-Grade Test of Mathematics. In addition, the study examined the North Carolina Foundations in Mathematics professional development program for teachers. This program, designed to increase a teacher's knowledge of mathematics, also helps teachers develop effective teaching strategies and to apply that knowledge in mathematics instruction. The study looked at the impact on mathematics proficiency and growth from students whose teachers have successfully completed the training program compared to those whose teachers have not. The study also examined teacher perceptions of barriers to successful implementation of a conceptual math program. The findings of the study indicate that the Math Expressions program had a statistically significant effect on the grade three through five student scale scores and growth. The Math Foundations training program did not show a statistically significant effect on scores from students whose teachers have successfully completed the professional development program. Barriers to implementation of the conceptual mathematics program included: fidelity of implementation of the conceptual mathematics program; lack of parent understanding of conceptual mathematics; teacher knowledge and understanding of conceptual mathematics; student understanding of mathematical concepts; need for staff development; and time constraints. [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.]