The purpose of this study was to explore the impact of an intervention on pre-service science teachers' self-efficacy to teach science through argumentation and explore the challenges they experienced while implementing argumentation. Forty pre-service science teachers in their final semester of schooling participated in an intervention that lasted for 11 weeks. Intervention focused on participants' understanding of argumentation as a scientific practice and as a pedagogical tool. The participants engaged in argument construction, evaluation, and critique, taught three argumentation lessons, engaged in peer observation of teaching, and reflection on their teaching skills. Data were collected through Argumentation Self-Efficacy Scale and an open-ended questionnaire. The results show that the intervention had a significantly positive effect on pre-service teachers' self-efficacy. Despite this reported self-efficacy, participants experienced significant challenges in guiding their students to construct scientific arguments and assessing the arguments developed by their students. Discussion focuses on implications for professional development of pre-service and in-service science teachers.