It is well-established that having a high-quality teacher can lead to long-lasting, significant effects on students' achievement. We know that teacher effectiveness reliably has an impact on student outcomes, but what impacts teacher effectiveness? One regularly recommended and prominent method for improving teacher effectiveness is through coaching. However, to date, the active components of coaching interventions have yet to be adequately specified, measured and investigated. The primary aim of the proposed study is to address this gap in the teacher coaching literature by examining which aspects of a coaching intervention, Making the Most of Classroom Interactions (MMCI), may lead to greater improvements in teacher effectiveness. More specifically, this study examined the influence of three process dimensions of coaching (i.e., coaching quality, ability to engage teachers, and rapport) on teachers' practice above and beyond other salient contributors to teacher effectiveness, such as content dimensions of the coaching intervention implemented (i.e., fidelity and dosage), relevant demographic variables and teacher burnout and self-efficacy. [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.]