Despite efforts to positively impact educational outcomes for underrepresented youth, the achievement gap persists in the United States. Underrepresented youth are students representing lower socioeconomic, racial, ethnic, or language minority populations that are underrepresented in higher educational attainment relative to their numbers in the general population. The persistent achievement gap has multiple implications for society. Lower educational outcomes are associated with lower future income levels, limited career opportunities, and other negative social outcomes. The achievement gap continues to exist in urban public schools. However, there are schools that have narrowed the achievement gap for historically underrepresented youth. The purpose of this qualitative case study was to identify school-wide practices that exist in one outperforming urban high school that is narrowing the achievement gap. This study focused on the manner in which resource allocation, existing programs, and processes for building staff capacity contributed to one high school's success. Data collection was conducted via surveys and interviews of school-site administrators and teachers, document analysis, and observations. Findings suggested that the case study high school narrowed the achievement gap through becoming a reflective organization, disrupting traditional structures, personalizing students' academic supports, and creating precise action plans focused on academic growth. By moving beyond merely implementing reflective practices and becoming a reflective organization, the case study school creatively implemented new solutions for personalizing supports for students. The urban high school also analyzed student data to create precise, growth-oriented action plans to positively impact student outcomes. This qualitative case study is presented as a blueprint for a school seeking to close the achievement gap. [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.]