The study aimed to examine the effect of argumentation-based teaching approach on developing prospective teachers' argument skills, and on their willingness to debate. The study employed the one-group pre-test-post-test experimental research design based on quantitative data. The participants consisted of a total of 192 3rd grade prospective teachers who were selected using maximum variation sampling method from the departments of Social Studies Education, Classroom Education and Mathematics Education in a state university in Turkey in 2019-2020 academic year. The data were obtained using the "Moral Dilemma Stories" developed by Rest (1979), and adapted into Turkish by Akkoyun (1987); and the "Scale of Willingness to Debate" developed by Infante and Rancer (1982), and adapted to Turkish by Kaya (2005). The data were analyzed via descriptive and inferential statistical analysis methods and Argumentation Assessment Rubric developed by Erduran, Simon, and Osborne (2004). The results revealed that the argumentation-based teaching increased the prospective teachers' argument skills and their willingness to debate. It was also found out that making use of such skills as researching, reasoning, discussing, expressing thoughts, and persuading, in student-oriented education systems in a more comprehensive way could be helpful to support the argumentation-based teaching approach.