The problem addressed in this study was the lack of consistency among United States (U.S.) Army instructors' support for students with low self-efficacy in a U.S. Army online blended learning course, which has a negative impact on deep learning. The purpose of this qualitative phenomenological study was to gain a better understanding of the perceptions of instructors on students' low self-efficacy in the U.S. Army Command and General Staff College's online blended learning course which has a negative impact on deep learning. The community of inquiry framework was the theoretical framework for this study. A purposefully selected sample of 10 instructors in the U.S. Army Command and General Staff College's online blended learning program was recruited. Data was collected through semi-structured interviews. Thematic analysis was used to identify themes, code data using NVivo software, and organize data into categories. The findings indicated that online blended learning students experienced low self-efficacy due to their experiences and lack of familiarity with online learning, learning activities that involved problem solving and critical thinking were most effective at promoting deep learning, and that instructors embraced their roles as facilitators to help their students overcome the self-efficacy challenges that impacted their deep learning. Recommendations for practice include revising faculty development programs to incorporate the community of inquiry framework, developing a standard orientation or onboarding process for online blended learning students, and substituting some of the learning activities that are less effective at promoting deep learning with activities that are considered more effective at promoting deep learning. Future research might include a mixed methods study or action research in the U.S. Army Command and General Staff College online blended learning program and ethnographic studies at other professional military education institutions using the community of inquiry framework. [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.]