Teaching has long been considered an isolated profession with little opportunity for collaboration. A major task for school leaders is to create improvement from within the school. Teachers are a valuable resource and each one possesses expertise in strategies and methodologies that can be a benefit to others. This action research explored the effects of peer coaching on instructional practice, use of common planning time, and teacher perceptions of peer coaching as professional development. A pilot study took place in a Pre-K-Grade 5 elementary school in which 15 participants utilized "The 2 + 2 Performance Appraisal Model for Collaborative Peer Coaching" designed by Dwight W. Allen and Alyce C. LeBlanc. Data collection instruments included an online survey before and after the pilot study. At the conclusion of the pilot study, two focus groups and four individual face to face interviews were conducted. Data analysis revealed that peer coaching impacted aspects of teachers' instructional practice. Participants reported an increased repertoire of instructional skills. Participants cited areas of growth in classroom management, knowledge of the curriculum in grades other than the one to which they are currently assigned and knowledge of students to assist in informing instruction. The frequency of the use of common planning time for collaboration was increased. Common planning time was utilized for collaborative planning and reflection of teaching practice. Scheduling time and finding time to conduct peer observations were the biggest challenges reported. Participants shared that peer coaching increased confidence and reduced isolation. Analysis of the qualitative data indicated that peer coaching was perceived as an effective means of professional development in part because it takes place in an authentic environment and is self-directed. Participants report an increase in motivation when learning is personalized or self-directed. [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.]