International recognition of Special Educational Needs Coordinators (SENCos) as agents of change for students with special educational needs calls for a deeper understanding of SENCo agency. However, literature on teacher agency for inclusion has paid little attention to SENCos. Taking a sociocultural view of agency, this qualitative case study collected rich data from five primary school SENCos in New Zealand via semi-structured individual interviews, work-shadowing and relevant documents. The findings showed that the SENCos exercised agency for inclusion through advocacy for students with SEN, commitment to the SENCo role, professional competence, self-efficacy, participation in decision-making, and collaboration with a wide range of people. The findings point to the need to conceptualise SENCo agency as a temporal, ecological process that involves engagement with culture, structure and resources in specific contexts.