This is a dissertation study regarding effective leadership practices in language immersion programs. Much of the previous research concentrates on students' academic achievement in immersion programs. The purpose of this research is to discover actions, attitudes, knowledge, and skills that immersion leaders of successful programs exhibit. Using a basic qualitative model, I interviewed principals, assistant principals, teachers, and parents at three schools with Spanish/English dual immersion programs. The findings indicate that the immersion leader must establish a positive culture through building trust, building community with parents and teachers, and showing commitment to the program. In addition, the leader must provide program and teacher support in a variety of ways, including the provision of professional development, differentiated professional development for international teachers, resources, and leadership opportunities. Finally, effective immersion leaders must possess specific knowledge and skills in order to lead a successful immersion program, including program knowledge, advocacy skills, and the ability to apply a shared leadership model. Being bilingual is considered an asset, but not required. Immersion leaders can learn from the applications for practice in their respective settings. Future research in this should include a wider range of program models and a more balanced pool of participants, including native target language speakers in dual immersion programs. Future research should also include a critical pedagogy lens in studying dual immersion programs specifically. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]