This paper examines two sides of a coin that relate to learning from dialogue. The first side of our coin relates to the role of dialogue in learning; the second side is related to the part that observations of learning dialogues can play in the design of computer-based learning environments. In order to define the scope of the paper, various complementary research question are examined. For example, one question is how and why does one learn from dialogue? A second question is how, or to what extent, can theories and studies of dialogue and interaction be exploited in a concrete way by designers of interactive media for education? Following a review of related literature I present my main argument, namely that the evolutionary approach provides a model by which research in learning, teaching and theories of interaction can jointly feed into the design process of learning technology. This is followed by an exposition of the evolutionary approach. There are three aspects to what I am terming an evolutionary approach to learning technology theory: (i) theories/models of teaching, learning and interaction, (ii) empirical observations of learning, and (iii) interactive learning environment design and implementation. The purpose of this evolutionary approach is the mapping out of not a specific theory, but how people are working towards the creation of theories. The evolutionary approach involves a constant process which slowly takes the educational technology field forward in iterative steps. In order to concretise the evolutionary approach, I examine the work of selected researchers, in the field of dialogue in learning, in the context of the identified three points of evolution. I conclude by suggesting that the evolutionary model can help designers of, and researchers into, learning technology in various important ways. Editors: Martin Oliver (UC London, UK) Reviewers: Sarah Fletcher (U. Bath, UK), Roger Hartley (U. Leeds, UK), Colleen McKenna (UC London, UK)