Labs have long been considered an important component of physics education. However,
while there has been progress in transforming physics education in physics lecture classes to improve student learning, less progress has been made in introductory physics labs. At the same time, the physics community has come to recognize that there is a need to transform instruction in order to improve equity and inclusion in the discipline. Inequities may be manifested in the curriculum, the instruction or, especially, interactions between students. In physics labs, where students typically work collaboratively in groups of 2-4 students, some of these inequities may be especially salient. This dissertation addresses the question of equity in introductory physics labs by considering student interactions, curriculum, and professional development for lab instructors. I report on qualitative studies that sought to outline mechanisms by which inequities are perpetuated and exacerbated in introductory labs, such as gendered task division, isolation, and stereotype threat. I conducted quantitative analyses to assess the impact of task division and diversity on student performance. I performed case studies of two lab transformations, shedding light on what works, and what slips through the cracks, when lab instruction is transformed. I analyzed the impact of transformed labs on student attitudes toward experimental physics, and I advance a framework for designing lab curricula and lessons to improve student learning. I developed and analyzed an approach to providing professional development for graduate student teaching assistants (TAs) who served as lab instructors. Finally, I analyzed student reflections about the impact of the transition to online learning.