School systems in PK-12 are being challenged to incorporate real-world learning into their curriculum to better prepare students for success after graduation (Karakas-Ozur & Duman, 2019). As high school organizations are beginning to apply authentic learning strategies, there is a gap in knowledge for implementation as much of the research has be conducted at the collegiate or adult learning levels. The research question: What are head administrators' and teacher participants, in three midwestern secondary authentic learning programs, perceptions of Authentic Learning Theory (ALT) best practices being implemented to achieve their program goals? This multi-case study used document analysis, interviews, and focus groups to find most promising authentic learning strategies of three high school authentic learning organizations. The study used the ALT, and more specifically Herrington, Reeves, and Oliver's (2009) Nine Characteristics to Achieve Authentic Learning Environments, as the theoretical framework. The research found an overarching theme to be a shift in mindset in head administrators and teachers. It also revealed new authentic learning practices beyond the nine characteristics of Herrington et al. (2009). This research provides a better understanding of ALT, its most impactful practices for practitioners at the secondary level, and data for future researchers. [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.]