Professional learning is increasingly understood as vital for the development of educators, and for the development of a strong educational system. We argue that the most essential purpose of professional learning is for the development of critical praxis. Critical praxis is related to action that is morally, socially and politically informed. This action is undertaken with an awareness of possible consequences together with the intention to make positive contributions to society and to humankind. Critical praxis in education is an intentional action (or associated reflexivity) informed by critical questioning related to the social, moral and political purpose of education. Critical praxis is tightly connected with learning experiences. This article looks at three examples of the development of critical praxis through professional learning, across three different educational settings. We explore the practice architectures that enable and constrain critical praxis in professional practice and identify three key themes in relation to the development of critical praxis: agency, power and relational trust. We argue that the potential power of professional learning is in supporting and developing the capacity to question institutionalised habits or educational practices that may be in conflict with values, purpose and moral intentions, in order to create positive change.