Prior work has found inequities in what experimental roles students take on during instructional labs. Research also suggests that this role division might arise implicitly and that prompting explicit role negotiation might improve equity in lab group work. To understand these various ways students negotiate roles in their lab groups, we use the lens of positioning to analyze two different video episodes of a gender-and-race-diverse group of three students. In one episode, students implicitly take on roles through subtle negotiations and in the second episode, one student explicitly assigns roles. We find that the positioning dynamics in both episodes lead to inequitable learning experiences within the group. This inequity, moreover, occurs along gender and racial lines, prompting future work relating students’ intersectional identities to their positioning dynamics in small groups. © 2022, American Association of Physics Teachers. All rights reserved.