Given a sociocultural framework of teaching and learning, argumentation and discourse become central elements of education, particularly in science education because of argumentation's key role in scientific communities. This study documents preservice teachers' perceptions of and aptitudes related to argumentation as they participated in a science methods course designed to promote discourse and argumentation. Data sources consisted of instructor reflections, course documents, and student work. Participants tended to view argumentation as a central element of science and as a means for promoting conceptual development in science classrooms. They were generally adept in the construction of arguments, particularly with respect to the evidentiary support of claims and demonstrated improved practice as the course progressed. Implications for using this course as a model and suggestions for its improvement are discussed.