<p>In recent years, more science classrooms include inquiry-based approaches to learning in response to advances in education theory and science curriculum reform efforts. Yet, extant research indicates there are hurdles to fully actualizing those benefits: learners’ regulation of cognitive, social, and motivational processes can be challenging. To help clarify processes implicated in inquiry-based science learning, the current study integrated developmental psychology research on adolescents’ peer relationships and friendships to investigate early adolescents’ understandings of the role of peer social relationships and friendships in collaboration in middle school inquiry classrooms. We thematically analyzed 32 interviews with 7th grade students from a U.S. middle school. Interviews occurred at the end of a semester-long inquiry-based curriculum implementation designed to promote authentic inquiry and argumentation. Results suggest that early adolescents primarily viewed both peer relationships generally and friendships specifically as beneficial to prosocial behaviors such as helping and ensuring fair consideration of one’s ideas, supporting argumentation, and supporting motivation by minimizing the adverse impact of competence and peer group belonging concerns on learning and promoting group cohesion. Early adolescents viewed peers as important resources regarding accessing alternative perspectives, explanations, and counterarguments. Early adolescents also distinguished between types of friends, favoring those who support group function and noting greater prosocial behavior with friends than other peers in collaboration. Findings suggest a need to develop scaffolds to counteract favoritism toward friends and status problems, as well as intervention on broader school norms to support forms of motivation that are conducive to inquiry dialogues.</p>