In this article, the early professional development of mature, early career teachers who entered the profession via an employment-based route to teaching in England is presented and explored from the teachers' own perspectives. From a larger sample in a longitudinal study, the development of four career changers is traced in detail, using a model of professional learning which highlights teaching and professional skills. There is some evidence that those who undertake the programme experience a smoother induction into teaching than those from more traditional routes, although the internship year itself is challenging and demands a high level of commitment and resilience on the part of the pre-service teachers. Contextual factors, such as school support and learning from experienced teachers, are vital in enabling early professional development and the absence of these can hinder learning and self-confidence. Findings are analysed with reference to the model, as well as research on teachers' development, within a socio-cultural learning framework. The study makes a valuable contribution to knowledge about the professional development of mature entrants to teaching. (Contains 1 figure.)