Since the introduction of the Coleman Report (1966), the focus on closing the achievement gap has been a critical component of educational policy for political leaders and field research by educators. The economic crisis which California and the nation at large currently face creates a challenging situation in attempting to narrow the gap. Cultural and economic implications are huge if public schools continue to fail in fully preparing minority and socioeconomically disadvantaged children. This study focuses on an outperforming urban high school that has sustained success toward closing the gap for more than 5 years. This school, which includes a largely Hispanic and socioeconomically disadvantaged population, was chosen for its accelerated and sustained student achievement. The research questions used in this study were developed by a thematic dissertation team of nine doctoral students from the University of Southern California. The study is a qualitative case study using a triangulation approach to identify the cultural norms, programs, and practices being used to close the achievement gap and sustain success. The data collection instruments include document analysis, interviews, surveys, and observations. The study revealed 11 findings that contribute to the sustained success of the school narrowing the achievement gap. The findings were (1) Data-driven decision making; (2) A consistent and clear message that failure is not an option; (3) Shared leadership; (4) Support of teacher leaders; (5) Getting the right people on the bus and in the right seats; (6) Collaborative culture; (7) Intervention by invitation is not an option; (8) College-going culture; (9) Rigor, relevance, and relationships; (10) Assessment for learning; (11) Strict focus on student needs. Questions raised for additional research include studying a school that would be more demographically equivalent in its black, Hispanic, and White populations; the role of teacher efficacy in forming a collaborative culture; teacher efficacy as a result of forming a collaborative culture versus good hiring practices; how the practices of successful urban high schools influence higher education; the effect of narrowing the gap in high school on higher education; and a comprehensive meta-analysis of trends that sustain success of narrowing the gap from K-12. [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.]