As science has become an integral component of today's technologically driven world, k-12 success in this subject is critical if continued American competitiveness in the global economy and workforce is to continue. An appreciable achievement gap exists in science performance, affecting racial minorities disproportionately. This reality forecasts a continuation of the already dismal representation for racial minorities in the STEM workforce. This dissertation investigates the policy, curricular and professional development practices of school leaders in Florida that experienced exceptional success educating students classified as racial minorities in science. Following a review of literature on the achievement gap and culturally responsive school leadership, a qualitative research project engaged state, district and school level leaders to address the central phenomenon, the methods of governance deployed in some of Florida's most proficient schools for eighth grade minoritized student achievement. The study also examined the recommended best practices of leadership from the National Science Teachers Association (2016) within seven purposively selected high achieving schools where the eighth-grade science achievement gap was reversed. A multi-method research design was developed and utilized phenomenological, grounded theory and multiple case study methodologies. An ex-post facto analysis of state and national data, along with the qualitative techniques of interview, questionnaire, focus group, and document analysis were used to triangulate the information collected. Seven schools that reversed the eighth-grade science achievement gap were selected. Following several iterations of data collection and a detailed coding process, nine best practices of policy, curriculum, and professional development were identified. Additionally, two emerging themes, higher expectations and a commitment to serving all students as needed attributed to the participant schools' successes. This research is especially relevant to state leaders, superintendents, district leaders in science, and all personnel seeking to educate students who have previously underperformed. Keywords: Achievement Gap, Science, NSTA, Educational Leaders. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]