With consistent pressure and an elevated sense of accountability for student achievement, campus principals need to maximize their resources and focus their leadership on academic areas that achieve the most success from students. Leading instructional coaches to engage teachers in the activities that teachers and principals view as most impactful to their teaching practices will allow principals to leverage the work of these highly skilled specialists and build teacher capacity. This mixed-methods, action-research, study identified the instructional coaching activities that teachers and principals determine to be the most influential in changing teachers' instructional practices. The frequency of specific instructional coaching activities used, as well as the strengths and weaknesses of the activities in improving teachers' practices, from teachers' and principals' perspectives, were also studied. The coaching activities studied encompass coplanning lessons with a coach, coteaching with the coach, reflective questioning by the coach, modeling by the coach, debriefing a lesson with the coach, classroom observation by the coach, and analyzing student data with the coach. The participants in this study were from a public school district in southeast Texas that utilizes an instructional coaching model at the elementary level. Quantitative and qualitative data from teachers and principals were collected using close-ended and open-ended questions on a survey. [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.]