This chapter examines how and why Lesson Study, a globally promoted model of teacher professional development, was introduced, adapted, and institutionalized in the postsocialist context of Kazakhstan. The chapter explores the transformation of Lesson Study from a collaborative, inquiry-based practice into a mechanism of performative accountability, as it became embedded within national teacher appraisal frameworks. Drawing on policy borrowing research and the concept of multivocality of policy transfer, the chapter highlights how global reforms acquire divergent meanings for different policy actors. Through the case of Nazarbayev Intellectual Schools and its Center for Teaching Excellence, the analysis traces how Lesson Study was initially positioned as an innovative approach for reflective experimentation and later reinterpreted to serve standardized performance metrics. To illustrate this trajectory, the chapter draws on policy document analysis and selected insights from qualitative interviews, shedding light on how teachers navigated Lesson Study both as a professional learning opportunity and a response to institutional expectations. The chapter argues that borrowed policies are not simply transferred but are reshaped through complex negotiations involving local histories, professional cultures, and state reform agendas. This analysis offers broader insights into the challenges of adapting global education reforms in postsocialist contexts and raises critical questions about teacher agency and the conditions for sustaining meaningful professional development.