The Mill Cities Charter School is a public urban charter high school founded on the Essential School Philosophy (ESP). Introduced in 1984, ESP “envisions an educational system that equips students with the intellectual, emotional and social habits and skills to become powerful and informed citizens who contribute actively toward a democratic and equitable society” (Coalition of Essential Schools, 2015). However, there is a lack of empirical research exploring the implementation of ESP, as well as its impacts on students’ personal, social and academic growth. Thus, this study’s goals were to gain an interpretive understanding of student perceptions and developmental impacts; as well as the process through which school culture influences positive youth development. A qualitative phenomenological approach was utilized, based on the philosophy of critical realism, which mediates between subjective experience and objective reality. In-depth, in-person semi-structured interviews were conducted on-site with 20 members of the senior class to explore their perceptions of the school culture and its impacts on their personal, social and academic development. Findings revealed that students largely had positive perceptions of school culture experience in all explored dimensions (Safety, Relationships, Teaching and Learning, Institutional Environment) with one notable exception, the School Improvement Process dimension, in which concerns were expressed about the school’s expansion plan changing the existing culture. Students also reported positive gains in personal, social and academic development, which they directly attributed to the school culture. Further, theoretical analysis revealed students’ internalization of cultural identity as the mediating process to explain “how” school culture positively impacted development. This relationship between individual and institutional cultural identity was bi-directional, with reciprocal impacts on both students and the school culture itself. This dissertation may inform educational policy discussions concerning the relationship between school culture and positive youth development. Findings regarding the ESP’s successful implementation into an urban public charter school setting and positive perceived impacts on high risk students’ development offer insights into the transformational elements of school culture. Significantly, this study offers understanding of this transformational process as a reciprocal interactive relationship between individual internalization of cultural identity and institutional externalization of a unique, recognizable organizational identity.