Recent worldwide education policy has reinvented teachers as agents of change and professional development of the school curriculum. Academic literature has analyzed changes in how teacher professionalism is conceived in policy and in practice but Teacher Agency provides a fresh perspective on the issue, drawing upon an ecological theory of agency. Using this model for understanding agency, Mark Priestley, Gert Biesta and Sarah Robinson explore empirical findings from the 'Teacher Agency and Curriculum Change' project, funded by the UK-based Economic and Social Research Council (ESRC). Drawing together this research with the authors' international experiences and perspectives, addresses theoretical and practical issues of international significance. The authors illustrate how teacher agency should be understood not only in terms of individual capacity for teachers, but also in respect of the cultures and structures of schooling.