The sustainability and institutionalization of change initiatives for school improvement dependent on a number of inter-related factors and many of which are cultivated through leadership. The focus of this study was to understand how school leadership sustains and institutionalizes change initiatives for school improvement. The study design was qualitative in nature. Two schools from each public and private educational system were selected, to understand the continuation of the innovations from two diverse outlooks and contexts. The focused, sustained change initiatives in this study were the initiation of the English medium section and school-based teacher professional development in the case study schools, respectively. The headteacher, professional development teacher, and two senior subject teachers from each school were the direct source of data collection for this study. Data were generated through multiple methods such as interview, observation, and document analysis. The findings of the study reported that despite working in a limited framework and resources, school leadership play crucial role as robust contributor in fostering educational changes and school improvement. It was also found that the close association and ongoing interaction of both the school leadership with the stakeholders stimulated and created a culture of collegial relationship in the schools. The involvement of stakeholders in decision-making, shared leadership, and provision of ongoing professional development opportunities created a sense of ownership, commitment, and determination among the staff members. As a result, they put their efforts collaboratively for the sustainability of the change initiatives and school improvement.