Job–embedded coaching, whereby an expert in a particular knowledge domain such as childhood disability, teaching, or special education actively works and collaborates with educators long–term, has been demonstrated to be a successful approach to developing educator knowledge and practice. In consultative models educators may consult colleagues within the school, such as health care professionals and fellow educators, or they may attend professional workshops. However, consultative do not efficiently address how educators can better support students’ learning challenges in daily teaching practice and this knowledge is difficult to attain through traditional short–term professional development. The learning, social, and behavioural needs experienced by children and youth with disabilities frequently stem from underlying complex health care needs and are oftentimes too challenging for educators alone to address. Using a realist evaluation framework––which examines what works for whom and how in a given setting–– this multiple case comparison critically analyzed two separate cases that used job-embedded coaching in Ontario schools to build educator capacity about teaching children with diverse needs within the general classroom. One case was grounded in the rehabilitation model of service delivery whereby the coach was an occupational therapist, and the other case was grounded in education and employed a teacher with training in special education in the coach role. Examining context revealed that factors beyond coaching were responsible for its success. The contexts to which the implementing leaders belonged informed project driver mechanisms (e.g., professional training, designation, perspectives and experiences, model of service delivery) important for service delivery, teacher, coach, and student outcomes. Community mechanisms associated with the environment in which coaching was implemented (e.g., community culture as well as school ethos and school priorities) also were important for all outcomes. The alignment of project driver mechanisms with community mechanisms was important for the way in which service delivery was adopted. Job–embedded coaching is an effective method of professional development and its success is greater when a congruency in beliefs, priorities and culture exists in collaborative partnerships. / Thesis / Doctor of Philosophy (PhD) / As research about childhood disability increases, teachers are becoming more aware that the difficulties students experience at school may be part of an underlying health–related or developmental problem. Teachers attend professional development workshops to learn new skills; yet applying those skills in the classroom is an ongoing challenge. Daily practice and long-term training are more effective ways to develop teaching skills. One way of achieving this is through job-embedded coaching. Job–embedded coaching involves an expert (in this case an expert on disability) who coaches the teacher in the classroom during classroom time about different teaching techniques that will include and benefit all students. This research describes how two separate Ontario research teams (one health-based and one education-based) used job–embedded coaching to improve teachers’ abilities to teach students with a variety of learning needs. In one project, an occupational therapist acted as the job–embedded coach, while in the other project, the coach was a teacher with training in special education. This research compared both projects to learn more about what made coaching work, for whom it worked for, how it worked, and why it worked. The findings of this research showed that reasons beyond coaching alone were responsible for its success. The approach, perspectives, and culture coaches brought to the schools were important and were influenced by the environments to which the research teams belonged. The alignment between coaches’ approaches and culture and the school’s culture and vision was important to the success of coaching as well as to teacher, coach, and student outcomes. Job–embedded coaching as a form of professional development does work and can be improved in the school settings with a shared understanding about students with complex learning needs.