The emergent perspective (Cobb & Yackel, 1996) is a way for researchers to conceptualize teaching and learning interactions that gives equal analytic focus to the social environment and individual cognition. According to this theory, individual students' conceptions and activities give rise to ways of reasoning that become accepted in the class community, called emergent mathematical practices. Students' participation in these practices then affects their personal conceptions and activities. In this study, I further contribute to researchers' understanding of the nature of this relationship by documenting the mathematical practices established in a class community and investigating a subset of individuals' subsequent reasoning in a clinical interview. In contrast to previous work, I found the majority of students interviewed reasoned in ways that were qualitatively different from the established practice. I then developed a partial explanation for how students could participate in class activities yet continue to reason in ways that differed from the established practice by examining the mathematical meanings constructed through the classroom discourse.