This study examined the relationship between the percentage of highly qualified teachers and standardized measures of student proficiency in the core academic subjects of mathematics, reading, science, social studies, and writing. Signed into law in January of 2002 by President George W. Bush, the No Child Left Behind (NCLB) Act requires teachers of core academic subjects to be highly qualified in subjects taught. According to the Association of Texas Professional Educators (2012), to be highly qualified under NCLB, a teacher must have "(1) at least a bachelor's degree, (2) full state certification, and (3) demonstrated subject-matter competency in the core academic subjects assigned" (p. 1). The study focused on all middle schools within the state of Tennessee. The relationship between the percentage of highly qualified teachers across all Tennessee middle schools and school-wide rates of attendance, promotion, suspension, and expulsion was also examined. Once those correlations were completed, the moderation of those relationships by the institutional characteristics of percentage of minority students, percentage of students in poverty, school locale/setting (urban, suburban, town or rural), and school enrollment were reported. Among the 292 middle schools that were able to be included in this study, bivariate correlations that were statistically significant were consistently observed between the percentage of highly qualified teachers at the school and standardized measures of student proficiency. Correlations between highly qualified teacher percentages and suspension and expulsion rates were also significant, meaning that as the percent of teachers deemed highly qualified increases, suspension and expulsion rates decrease. In regards to moderation of the findings, significant correlations between Tennessee Comprehensive Assessment Program (TCAP) outcomes and percentages of highly qualified teachers were present both between high and low percentage subgroups of middle schools by poverty level and by the high percentage subgroup of middle schools for the minority student classification. The findings of this study suggest that teachers holding highly qualified status are especially needed in schools with a high minority and/or high poverty student population in order to ensure that all students move forward academically at an appropriate pace. According to the results of this study, the highly qualified teacher mandate's (HQT) main purpose of helping increase student proficiency levels on standardized exams is being met along with the unattended outcomes of lowered suspension and expulsion rates. School-level administrators as well as district-level personnel should maintain concerted efforts to recruit and maintain highly qualified teachers of core academic subjects for the goals of ensuring adequate student academic progress and decreasing the frequency of student suspensions and expulsions. [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.]