This paper examines the influence of Iranian teacher unions on educational policy reforms, focusing on the evolution of teacher unions over the past two decades. Our key finding reveals a shift in the discourse and mental model of Iranian teacher unions, with an increased emphasis on education policy changes for quality and equity education. However, the unions have not yet been able to advocate successfully for educational policy reforms due to the country's changing political and social climate, limited resources, and lack of access to international networks. Our study has revealed key factors that have contributed to a shift in Iranian teachers' attitudes from bread-and-butter unionism to social justice unionism. These include the creation of more inclusive unions, the decentralisation and democratisation of union structures, the use of social media to amplify their message, and the formation of coalitions with social justice groups. Despite encountering challenges, our findings suggest that teacher unions can be crucial in advocating educational policy reforms in countries facing significant obstacles.