In recent years, there has been an increase in the popularity of personalized learning (PL) and educational technology in American K-12 schools. In particular, school models that use technology to deliver personalized learning experiences for students have proliferated. Still, few studies have investigated these phenomena in K-12 contexts, with no studies to date examining the implementation and evolution of PL models over time. Toward closing this gap in the current literature on PL models, this qualitative case study uses Activity Theory to understand how and why a PL school in the United States evolved from its inaugural year through its third year of implementation. Findings indicate that the school exhibited substantive changes in organizational practice rooted in: (1) a disconnect between vision and practice; (2) the implementation of a "No Excuses" model and the school-level prioritization of accountability; and (3) the reprioritization of PL. Implications for educators and organizations interested in developing and implementing PL are discussed.