<p>All teachers mediate curriculum, even in countries with highly prescribed curricula. How this occurs equitably, despite global constraints such as accountability and performativity pressures, remains an area of investigation for both teachers and researchers internationally. Our research delves into teachers’ curriculum making practices in language diverse mathematics classrooms, an area that is currently underexplored. It examines how and why teachers mediate a prescribed maths scheme in equitable ways. We propose the ecological approach to teacher agency as a suitable theoretical framework to investigate teacher mediation of curriculum making. Drawing on interviews and observations in England, alongside relevant literature, we examine these mediation processes. In particular, we highlight the role of teachers’ beliefs, professional histories, social structures, material and relational resources which may enable or hinder teachers to achieve their agency for equitable practices. By illuminating a common international dilemma regarding how prescription can be mitigated through equitable and agentic teacher practices, this paper offers practical, methodological, and theoretical insights for teacher education, future research, and policy to better support teacher agency in ever-changing and diverse classrooms.</p>