This study compared data related to National Board Certification (NBC) of mathematics teachers in a South Florida school district. Data included 1,162 student scores on the 2014 AP Calculus AB exam, student gender, student grade level, and eligibility for free or reduced price lunch (FRL) status. Teachers completed the Standards' Beliefs Instrument (SBI) (Zollman & Mason, 1992) to determine alignment of their beliefs with the National Council of Teachers of Mathematics (NCTM) standards. Interviews were conducted with five NBC mathematics teachers to understand how they incorporate best mathematics teaching practices in their daily instruction. A t-test analysis revealed that students taught by NBC teachers scored significantly higher (M = 3.70) on the AP Calculus AB Exam than those taught by non-NBCTs (M = 2.74); Cohen's d (.6429) indicated a moderately large effect size. No causation is to be implied; various confounding factors may also contribute to the variance in student scores. Three factorial ANOVA tests were performed to test interaction effects. Two significant interaction effects were detected: (1) NBCT status and student grade level; and (2) NBCT status and student FRL (free and reduced price lunch) status. No significant interaction was found between NBCT status and student gender. With a reliability estimate using Cronbach's alpha, a second t-test was conducted. A statistically significant difference was found regarding the mean scores of NBCTs and non-NBCTs regarding their beliefs according to the vision of the NCTM. NBCTs generally have practices that align more with the NCTM mathematics teaching standards. Interviews with five NBC teachers of AP Calculus provided rich qualitative descriptions of their teaching philosophies, approaches, and best practices contributing to student success. The results of this study reinforce evidence from previous research that the process of obtaining the NBC contributes to a teacher's professional expertise and is related to student success; however, since there may be other confounding factors related to teachers, students, and their schools, the NBC cannot be considered the sole factor contributing to student success in AP coursework and exams. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection