Instructional coaching has been a part of educational communities for decades as a way to support teachers, improve instructional practices, and support student achievement. Research has been conducted on various models for instructional coaching with varying levels of proven success. As new policies are implemented, instructional expectations have changed, and there is a greater need for instructional coaching support. While it is known that certain coaching models are effective, there is an underlying factor that impacts the level of effectiveness of coaching: teachers' openness to instructional coaching. Through a qualitative case study conducted at a K-12 school district in California's central valley, I sought to understand the reasons why some teachers are open to coaching. Interviews with nine participants resulted in one main theme and three subthemes. Within the theme of trust, subthemes related to openness to coaching and the influence of mental models were revealed: (1) a willingness to engage in instructional coaching; (2) coaching attributes that foster development of a trusting relationship; and (3) strategies that instructional coaches use to increase a teacher's openness to coaching. The thematic finding of trust was prevalent throughout the data. Across the data, the concept of trust was ubiquitous as a factor that fostered teachers' initial and ongoing relationships with instructional coaches. Included within the theme of trust, mental models emerged as participants shared their experiences related to instructional coaching. Teacher participants noted experiences based on mental models that motivated them to seek out coaching and the development of new mental models based on experiences they had throughout the coaching process. Additionally, coach participants noted experiences based on mental models that guided them in how they supported teachers throughout the coaching process to encourage persistence in coaching. Based on these findings, recommendations include supporting instructional coaching programs through deepening district level understanding of effective coaching programs, professional development opportunities for new and current coaches, and site administrator training on effective engagement with instructional coaches. [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.]