Smartphones, laptops, and tablets are mobile devices that are now considered essential tools for high school educators. The problem many teachers face is figuring out how to manage multiple mobile devices in the classroom at the same time. The purpose of this qualitative case study was to explore the barriers, problems, and challenges teachers experience while using these devices in the classroom. The concerns-based adoption model provided the framework to analyze the informational, personal, management, and consequence stages of concern through in-depth interviews with 10 Catholic high school teachers in California. The results of thematic analysis showed that although teachers were already using mobile devices in their classrooms, the use of multiple devices simultaneously can magnify issues that existed with the use of a single mobile device. Self-efficacy was a concern because teachers lacked the professional development to support the use of multiple devices for instruction. Participants stated that investing in a good learning management system helped to relieve the pressure of not having a unified platform for students with different devices. Participants also expressed the benefit of having a clear policy that would maintain an active learning environment by keeping students accountable for their learning. Finally, participants expressed concerns with the barriers of accessibility and connectivity for students who had outdated devices. Providing teachers with the resources and training to manage multiple mobile devices can be a catalyst for positive social change to make multiple mobile devices effective tools for instruction in high school classrooms. [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.]