Abstract
Empirical studies examining these dynamics through the experiences of union leaders are limited, resulting in a significant gap in understanding how unions contribute to sustainable educational development. They do very little to provide an understanding of the root causes of resistance to transformative agency. This implies that these insights warrant deeper research to provide further clarity. It is within this context that this paper employs a narrative inquiry approach to provide detailed, contextual accounts of how union leaders navigate structural constraints, influence policy, negotiate power dynamics, and promote equitable, fair, and developmental practices for all stakeholders they aim to serve. This study explores how resistance can be framed and translated into transformative agency, demonstrating that teacher unions, often perceived as being opposed, can serve as key catalysts for institutional, professional, and social development within educational systems. Sixteen participants, including four principals, four members of the school management team, four members of the school governing body, and four members from various teacher unions, were interviewed. Data were collected through interviews. Data were analysed through the thematic data analysis method. The findings suggest that effective teacher union leadership entails strategic advocacy, reflective practice, and collaborative engagement, thereby contributing not only to the professional growth of teachers but also to the broader objectives of sustainable development in education. Therefore, this ensuing research advances the comprehension of teacher unions' developmental role, providing practical and conceptual insights for policymakers, school leaders, and stakeholders aiming to leverage leadership for systematic educational transformation.