The Next Generation Science Standards list scientific argumentation as one of the essential skills for students in K-12 education. Unfortunately, many teachers enter the classrooms without sufficient experiences with or knowledge of, this skill. A discourse analysis of twenty-one preservice teachers was conducted to study how preservice teachers constructed arguments within small group activities. Findings indicated that the preservice teachers used discourse to establish epistemic authority and deontic status within their small groups. Overall, the findings reveal how preservice teachers use discourse and add understanding to the research gap in argumentation discourse. The study has implications for teacher educators.