Successful teacher professional development (TPD) programs involve teachers in learning activities which are similar to the ones teachers will use with their students. If professional development is considered a learning process that teachers have to carry out, then their attempts to fulfill their professional needs through improving their performances can be considered as a developmental process. Teacher professional development is both contextual and historical. In this theoretical article, three concepts from Vygotsky's Cultural-Historical Theory (CHT) will be applied to TPD in order to contribute to the development of the literature on TPD and TPD programs: historicity, mediation and internalization. The claim is that successful TPD needs to legitimize the subject's history, use tools/models/techniques and strategies to mediate understanding, learning and development in a specific subject, and internalize change and development first socially before individually. Based on a review of the TPD literature and experiences from two longitudinal studies in English language teaching and natural science teaching, the article concludes that a Vygotskian perspective on TPD leads to the avoidance of isolating school from society and everyday life.