The article presents a case for the promotion of argumentation in science in preservice teacher education. In recent years, argumentation has emerged as a significant goal for teaching and learning of science. As an important aspect of scientific inquiry, argumentation plays a role in the generation and justification of knowledge claims. The theoretical background on the role of argumentation is reviewed and an empirical study is reported on the ways in which teacher training can be supported in the use of argumentation in science classrooms. Case studies of two Turkish teachers are used to illustrate how teachers structure lessons and support argumentation in secondary science classrooms after a series of training sessions. Results indicate that the teachers incorporated those features of pedagogical strategies (e.g. group discussions and presentations) targeted by the training.