Science educators increasingly seek to support students' participation in scientific practices, particularly epistemic practices, that is, those that ground authority for knowing in the discipline. Argumentation is one practice that has received significant attention in the research literature. However, scholars who take a sociocultural stance increasingly suggest that current conceptualizations are not sufficient for characterizing and supporting important aspects of scientific practice. In this article, I explore how students' argumentation can be brought into closer alignment with that of scientists. I identify consequential differences in the contexts in which scientists and students typically enact argumentation and discuss how these differences have been addressed in the literature. Finally, I propose several directions for further research: embedding argumentation in uncertain scientific activity, supporting students to contest both what they know and their means of knowing, building more carefully from students' resources, and attending to the development of epistemic cultures in classrooms.