The success of school communities and their stakeholders is determined by the leadership at the helm of the organization, as the arc of decision-making lies within their hands. Therefore, an analysis of principals' decision-making processes and their potential impact is of great significance. In the realm of decision-making, "systems thinking (ST) is an approach advocating thinking about any given issue as a whole, emphasizing the interrelationships between its components rather than the components themselves" (Shaked & Schechter, 2013, p. 2). In view of this approach, a study into the application and use of systems thinking may provide leaders with compelling insight into the decision-making processes of principals. As such, the purpose of this phenomenological, qualitative study was to explore the extent to which principals of elementary and middle schools within New York State used systems-level thinking in their decision-making processes relative to internal and external factors influencing a school's organization and its potential effect on culture and student performance. Further, the researcher engaged the participants in semi-structured interviews to distinguish the actions of systems thinkers by analyzing the narrative accounts of principals' experiences relative to their decision-making processes. The researcher discovered seven findings demonstrative of principals' use of systems thinking within the decision-making process: (a) collaborating with stakeholders, (b) collecting various sources of data, (c) considering an array of variables and examining the interconnectivity of the parts within their educational organization, (d) envisioning plans to design opportunities to engage stakeholders, (e) considering the internal and external elements that impact a school organization, (f) conceptualizing the interrelatedness of the parts within and beyond the structure of a school organization, and (g) considering the internal and external elements that impact a school organization. Conclusions were derived from the seven findings ascertained in the data analysis process. The researcher concluded collaboration to garner multiple perspectives of stakeholders was at the forefront of the decision-making process of principals. Additionally, principals collect data sources across varied points of a continuum, specifically, prior to enacting a decision, throughout the decision-making process, and as a means of reflecting upon past decisions. Further, characteristic of many leaders in the role of principal, is the act of considering a multitude of variables centered upon the impact on scholars to inform the decision-making process. Moreover, inherent within the decision-making process of many principals is the examination of the interconnectivity of the parts within school communities as a means of discovering the potential impacts of decisions. The researcher also concluded, to develop a comprehensive understanding of school communities, leaders consider the internal and external elements that impact their organizations to enact strategic decisions. Additionally, a central aspect of the decision-making process of principals is envisioning: the development of a vision or future image of their school community as it establishes a framework from which to design school-wide goals and potential plans of action. Finally, to strategically engage in the decision-making process, principals conceptualize the interrelatedness within and beyond the structures of their school organizations to gain an understanding of a myriad of impacts derived from the multitude of causes and effects attributed to enacted decisions. Systems thinking may provide the conceptual framework necessary to enact strategic decisions to ensure the continuous improvement of schools (Shaked & Schechter, 2013). As leaders are able to consider the parts in the context of the whole, a deep analysis of feedback loops may be conducted in an effort to understand the impact of decisions across the layers of school organizations (Shaked and Schechter, 2018). This process may be instrumental as it may enable leaders to view the full scope and potential trajectory of past, current and future decisions as a means to make continual modifications as the impact of decisions unfold. [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.]