This study focused on the impact of a new observation tool for principals to utilize and the effects it has on improving teachers' instruction and influencing best practices. The action research project explored the impact and influence that a well-developed observation tool could possess to help address areas of need; essentially, focusing on how administrators can develop their teachers through providing them with objective feedback and support during the observation process. The ultimate goal of this action research was to gain meaningful input on how to improve teacher practices through providing effective supervision and informative observations in a large city public school system. The methodology incorporated a qualitative research design. Data was gathered related to the impact of the principal observation tool on teachers' practices; it was gather in two phases. Phase one included a pre-intervention survey and a focus group discussion. Following the intervention (Phase two), a survey was conducted and discussions with research participants were held. In collecting the baseline data, factors were identified about the observation tool that illustrated the need for a more reflective observation tool to impact teachers' growth and development in the classroom. The data also helped to establish clear guidelines that principals could utilize to build effective teacher capacity and administer professional coaching in the observation process. The results of the research indicates that teachers benefit more and build best practices when principals, following the clinical supervision process and utilize an observation tool that provides extensive feedback, giving teachers more information and opportunities to enhance their classroom instruction. The study assists educational administrators on how to improve the learning environment by supporting their teachers with effective supervision using the observation tool as a direct channel to develop teacher instruction and empower best practices. [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.]