Research in effective programming for English language learners has demonstrated the efficacy of dual language education as a model for closing persistent achievement gaps for this growing population of students. With goals of high academic achievement, linguistic proficiency in two languages, and cross-cultural proficiency, dual language education is an enrichment model of education that eschews the deficit thinking often associated with language-minority students. Based on the promise of enriched education for all participants, the number of dual language programs is increasing nationwide. As districts across the United States plan for the implementation of dual language programs, identifying effective leadership practices for sustaining these programs over time is critical to the strategic deployment of human and fiscal resources. This collective case study examines best practices in dual language programs from a leadership perspective, with a focus on transformational and transformative leadership theories. District level policies and practices are discussed as they relate to the support of dual language programs over time. School level leadership practices are examined in the context of best practices in dual language education as they integrate with concepts of transformational and transformative leadership paradigms. Findings indicated that the actions of district leaders were crucial to the sustained implementation of dual language programs, as they supported the work of school leaders in five categories of leadership practice: vision, goals and priorities, high performance expectations, allocation of resources, and collaboration and shared decision making. Without the support of district leadership in these areas, school leaders struggled to recruit and retain qualified teachers, and minimum expectations for program design and implementation were not fulfilled. Written policies were not followed, and consistent, on-going professional development was not provided for dual language teachers or school leaders. Because these essential components were missing, the promise dual language programs hold for increasing student achievement could not be realized. [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.]