Purpose, scope, and method of study: The primary purpose of this study was to examine the relationship between teacher-licensure level in the New Mexico Three Tiered Licensure (NM 3-TL) System and gains in student academic achievement in reading and mathematics in grades four and five. A secondary purpose was to determine whether student socioeconomic status and/or student ethnicity contributed to the relationship. Stepwise multiple regression analysis was used to determine which of the possible combinations of the three variables best predicted gains in student academic achievement. The sample used for data analysis involved 129 teachers and 2012 students taught by those level-I, level-II, and level III teachers. Findings and conclusions: Results of the analysis revealed that there was a relationship between teacher-licensure level within the NM 3-TL System and gains in student academic achievement in both reading and mathematics. As teachers progressed through the NM 3-TL System, student scale scores increased for both reading and mathematics. Although the results of this study indicated that teacher-licensure level within the NM 3-TL System had a positive relationship with gains in student academic achievement in mathematics, those gains were independent of student ethnicity and student socioeconomic status. Gains in reading were independent of student ethnicity. However, there was a positive relationship between student socioeconomic status and reading achievement. [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.]