The authors had been using a system for stimulating discussion and debate among professionals as part of their education and continuing professional development. Hand-held technology for gathering and reflecting upon individual judgements had been shown to work, and the participants liked it. But a theoretical foundation of why and how it worked appeared to be lacking. The authors find the work of Vygotsky extremely helpful in explaining why student-student conversations can be a positive support to the learning process. In this paper they present a description of one of the professional settings in which student-student conversations have been used in stimulating learning. They relate this to a theoretical framework of conversations in intellectual development drawn from Vygotsky, and contrast it with alternative frameworks that place greater emphasis upon the role of the tutor who knows the ‘right’ answers and ‘corrects’ the learners.