In teaching social justice, educators draw from a diverse array of theoretical approaches. In so doing, analytically distinct concepts can get conflated, which significantly impacts student learning, particularly as they relate to teachers' social justice goals. Using ethnography, this paper examines how a social justice educator mobilized a Freirean pedagogical approach to teach students about their positionalities, and how this resulted in the conflation of "identity" and "positionality." In particular, I examine how a social justice educator's practices led students to understand positionality as identity, and to see identity as a fixed and essentialized personal characteristic, rather than a socially constructed power relationship. Ironically, this led students, particularly students from positionalities of relative privilege, to reject the instructor's call for students to participate in social action because they understood themselves to be defined by their identities, rather than by their actions. This paper contributes to the literature in social justice education by: (1) highlighting how the mobilization and conflation of analytically distinct concepts -- in this case, "identity" and "positionality" -- impacted student learning; (2) illustrating how the conflation of "identity" and "positionality" resulted in essentialized notions of identity that negatively impacted students' commitment to social action; and (3) arguing for a more intentional, historicized focus on positionality for social justice educators.