This purpose of this descriptive case study was to explore teacher knowledge of cultural proficiency as it relates to student achievement in a large, North Texas school district. In addition, the case study investigated teacher attitudes toward and perceived barriers to implementing a district cultural proficiency initiative. The following research questions guided the study: what knowledge did teachers have about cultural proficiency as it relates to student achievement, what were teacher attitudes toward a district cultural proficiency initiative, what barriers did teachers perceive in implementing a districtwide cultural proficiency initiative, and what opportunities did teachers perceive in implementing a districtwide cultural proficiency initiative? Three hundred and twelve teachers from a large, North Texas school district completed a survey about the attitudes, beliefs, and behaviors of teachers who work with culturally diverse students. From the survey results, twelve teachers were interviewed to develop a more detailed understanding of their knowledge of cultural proficiency and explore their perceptions about a proposed district cultural proficiency initiative. The results indicated teachers had some knowledge of cultural proficiency as it relates to student achievement. Although they were unaware of the district initiative until they were interviewed, participants showed support for the district's focus on cultural proficiency. The interviewees suggested several barriers to the successful implementation of the initiative, including: employee resistance, a scarcity of resources like district funding and a lack of time in teachers' schedules, as well as the possibility that district leaders might not plan the initiative as carefully as necessary for a successful outcome. Participants identified several opportunities for the district to accomplish additional goals while implementing the cultural proficiency initiative, like strengthening relationships between district employees and community stakeholders, creating safe, healthy, and nurturing schools, and improving student achievement. This study may be of interest to educational leaders seeking to increase the cultural proficiency of their organizations and employees. [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.]