In physics lab groups, students experience a wide range of equitable and inequitable interactions. After observing videos of students collaborating in an introductory physics lab, we defined that an equitable group is one in which every student’s bids are heard by their peers. We developed a methodology to characterize different lab groups by tracking students’ bid exchanges and assessing their levels of inchargeness. The analysis of equitable and inequitable groups showed that lab groups where one student is in charge can be equitable, as long as each group member’s opinions are acknowledged. We also found that gender and inchargeness do not sufficiently predict the equity of student groups. Based on these results, we argue that students that are in charge use their inchargeness to make their groups either equitable or inequitable. Future work will explore whether additional variables interact with inchargeness to predict levels of equity in group work. © 2020, American Association of Physics Teachers. All rights reserved.