This is a personal account of how teachers learn more about their teaching, recognising and building on the complexities of learning, of teaching and of human interactions. For 15 months I worked alongside a group of 20 experienced secondary science teachers engaged in a professional development project to explore and share understandings about teaching. We interacted both in day-long meetings and in their schools where I observed and recorded their conversations and actions. With regard to teacher professional development I highlight the importance of considering the roles and views of the teacher participants, of situating the learning in their practice in ways that also enable them to reflect, and of using a framework of principles that are significant to them. In considering teacher learning I have highlighted its complexity and personal nature and developed a new framework of greyative tensions which provide insights. I have described seven examples of greyative tensions, suggesting that teacher learning is simple and complex, planned and spontaneous, active and reflective, individual and communal, specialised and general, practical and theoretical, and formal and informal.