The research on conceptual change has so far mainly dealt with cognitive outcomes, but especially during the last few years there has been a growing interest in and discussion about the processes of conceptual change. The purpose of the article is to contribute to this discussion and to present a theoretical model of the dynamics among the cognitive and motivational factors in conceptual change. Several researchers in science education have proposed cognitive conflict as instructional strategy for teaching difficult scientific concepts. However, we aim to explain why it does not always support the conceptual change. In our model, the two crucial aspects to the process of conceptual change are: the sensitivity to the novel aspects in the situation, and the ability to regulate the tolerance of ambiguity resulting from the experience where the prior knowledge is not adequate.