Argumentation as a form of scientific discourse is a powerful tool that allows students questioning, justifying, and evaluating their and others’ claims. In science education, transmissive teaching predominates and this leads to difficulties in students’ construction of arguments and highlights limitations in teachers' pedagogical abilities in the management of this type of activities. Also, teachers' beliefs and perceptions have a big influence in the way they teach. Thus, the purpose has been to investigate pre-service primary teachers’ beliefs of what would be the skills they need as a core to support argumentation in science classrooms, and what skills students can develop when participate in science lessons based in argumentation. Results show that Pre-service Teachers of Primary pay little attention to the skills they will need in order to manage different methodological strategies as debate, pair work or pair discussion, that support the argumentation approach. Moreover, they lack of awareness about what is a good argument and its components, besides scientific knowledge. These results are significant because they indicate a need in designing specific training programs to support teachers in acquiring knowledge and skills about argumentation.