This study approaches the problem of African American mathematics achievement from a strength-based perspective, identifying practices implemented by middle school principals successful in increasing and sustaining the mathematics achievement of African American students. The study was designed to answer questions regarding both school-wide practices and those targeted directly toward achievement of African American students. Quantitative data was collected and analyzed for descriptive statistics through the use of a survey instrument sent to a purposeful sample of 67 middle school principals in California, followed by the collection of qualitative data through interviews with 4 principals. Several themes emerged from the data, including the use of structured teacher collaboration in several areas: the development of school culture and consistent expectations, pacing and planning of lessons and student products, developing formative assessments, and analysis of data. The development of positive relationships was another commonality, with principals indicating such relationships aided in the increase of student achievement through developing positive school culture, honest collaboration between teachers, and a feeling of inclusion for students in the instructional process. Although principals were selected for the study based upon above-average performance of African American students in mathematics, few of the strategies employed were targeted directly toward this group, with principals focusing instead on quality first instruction and high expectations for all students. The findings of the study provide a framework of effective practices to be utilized by middle schools currently not experiencing similar levels of success in increasing mathematics achievement and closing gaps for African American students. [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.]