In the face of colonial efforts to extinguish Indigenous language and culture, Kanien'keha:ka (Mohawk people) have been working to revitalize Kanien'keha (the Mohawk language) since the 1970s. However, Kanien'keha continues to experience greater speaker loss than gain. Through a comprehensive vitality assessment, this dissertation examines the continued causes of Kanien'keha decline and argues that adult second-language (L2) speakers play a crucial role in revitalization as they are essential for establishing critical speech domains, populating language revitalization structures, and restoring intergenerational language transmission. Kanien'keha:ka have created full-time adult immersion programs that are uniquely designed to create advanced young adult L2 speakers. This dissertation highlights adult immersion as the most effective and expedient pathway to create speakers, and argues that concentrated efforts to strengthen, expand, and perfect adult immersion are essential in advancing Kanien'keha revitalization. The foundational components of an effective adult immersion program are described, as well as the challenges that these programs continue to face. As an applied contribution, this dissertation also provides a scope and sequenced curriculum organized into structurally-based units for the second-year of Kanien'keha immersion programming, a period in program delivery that moves L2 speakers from intermediate to advanced speaking proficiency. Overall, this work seeks to increase recognition and understanding of the importance of adult immersion programs for so that they can become more prominent and stable institutions in strategies to revitalize Indigenous languages. [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.]