Supporting student engagement in science practices requires rethinking how classroom learning occurs, specifically in terms of the interactions that help students build their own knowledge. The types of student-driven exchanges fundamental to the science practice of argumentation differ greatly from traditional classroom interactions. To help classroom talk shift toward encompassing this practice, it is important to develop understandings of discourse patterns related to argumentation. Several analytic techniques have been used to examine a classroom's engagement in argumentation. However, new methodologies are needed for capturing and characterizing the complex, social dimensions of this science practice. This study explores social network analysis (SNA) as a means by which to attend to this demand. Specifically, this study utilizes SNA on data from two middle school classrooms that participated in an argumentation discussion called a science seminar. Sociograms (images of social relations derived from the SNA) offered visualizations of interactions during the science seminars, highlighting who exactly partook in the various aspects of argumentation, how, and to what degree. Findings suggest the importance of argumentation research examining ways to better support changes in classroom interactions. This study also points to the benefits of using SNA with other types of representations to capture a classroom's argumentation.