Even though there is no common conceptual basis guiding teacher education in Canada, over the past two decades teacher educators both in Canada and around the world have called for teacher candidates to become agents of change. While researchers across Canada strive to demonstrate "how" to prepare pre- and in-service teachers to be agents of change, few scholars have examined in detail what teacher agency might mean in the Canadian context. This paper reviews the conceptualisation of agency from five theoretical perspectives (psychology, sociology, critical theory, historical studies, and post-structuralism) and examines "how" empirical studies in the Canadian contexts align with these perspectives. This paper makes explicit the connections between the "how" and the "what" of agency, and as such informs current approaches to preparing pre- and in-service teachers and their potential role as agents of change, and maps out how the notion of agency is taken up in a particular jurisdiction.