Instructional coaching has come to the forefront as a means to build instructional capacity through shared collaborative experiences. The purpose of this qualitative case study was to investigate the relationship between instructional coaches and teachers. This study investigated three questions: (a) What qualities of the relationship between instructional coaches and K-3 teachers influence their collective efficacy? (b) How might the self-efficacy of the teachers and instructional coaches influence their collective efficacy? and (c) What effect does the coaching partnership have in the co-construction of knowledge between the instructional coach and the teacher? Participants included four coach/teacher partnerships from four school districts in a Midwestern state. This qualitative inquiry procured data through (a) individual interviews, (b) observations of coaching conversations, and (c) teacher self-efficacy and collective-efficacy surveys. Using a recursive data analysis process, I triangulated the data to verify the findings. Key findings revealed characteristics clustered into three major themes: (a) interdependence, (b) intentionality, and (c) agency. It was revealed that when the characteristics worked in conjunction with one another, the coach/teacher relationship was enhanced, which resulted in increased collective efficacy. The results of this study can inform district level leaders, building level principals, instructional coaches, and classroom teachers on the effects of agency, interdependence, and intentionality on the co-construction of knowledge and ultimately collective 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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]