This article details a professional development process with a group of teachers and educational psychologists in the UK, at a school for children identified as having social, emotional, and behavioural difficulties. The project focused on how teachers use conversation to include children within dialogue and incorporate children's ideas within the learning process. Through reflective and exploratory discussion, enhanced by videos of interactive sequences within classes, teachers explored and developed aspects of their interactional styles. Videos were compared from the beginning and end of the project showing considerable changes in how teachers and children participated in classroom conversations. Changes included the teachers using conversation to build more on children's ideas and actively support the cooperation between children. Changes in the nature of talk amongst children showed evidence of building more on ideas within conversations and making less new initiatives. The changes in conversations are considered with reference to children's participation and learning. Educational psychologists working alongside teachers in this way allowed assessment and intervention to occur at whole class and school level. The process of collaboration with teachers is considered with regards to the process of change, the use of video enhanced reflection and the nature of conversation in professional development. (Contains 4 figures.)