The purpose of this research study was to examine leadership behaviors of middle school principals who have been successful in stimulating and sustaining African-American students' mathematics achievement on the California Standards Test. Specifically, this research sought to answer the following questions: 1) How do middle school principal leaders stimulate and sustain mathematics achievement in African-American students; 2) What school-wide systems and practices do middle school principal leaders implement to promote mathematics achievement; and 3) What are the expectations of middle school principal leaders for the monitoring and assessment of mathematics learning prior to the California Standards Test? Using a mixed-methods approach to gather survey and interview information from 35 middle school principals in California. The results of the study revealed four motifs that stimulated and sustained mathematics achievement, four systems and practices that promoted mathematics achievement, and three monitoring and assessment systems and three subsystems to monitor and assess mathematics learning prior to the state assessment. As evidenced by their ability to stimulate and sustain African-American students' mathematics achievement for three sustained years on the CST, these principals' leadership behaviors did, in fact, have a positive impact upon African-American students' achievement. This study contributes to the body of research on leadership behaviors and its impact upon student achievement, and it reveals that African-American students can achieve when principal leaders employ the necessary leadership behaviors. [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.]