Undergraduate field courses provide students with valuable opportunities to learn in and from the natural environment. Prior research shows that field courses can improve students' cognitive and affective outcomes and encourage them to engage in social interaction with their classmates and professors. Despite frequent documentation of the ability for field courses to promote social relationships, no prior studies have characterized student interaction in this context or its influence on student outcomes. To better understand student interactions, we used social network analysis to characterize how and with whom students formed communities in a semester‐long field course with an integrated research project. We found that students form small, tightly connected communities composed of professional and personal contacts with whom they maintain contact throughout the semester. We asked students what they discussed when talking about their research project with their professional and personal contacts. We found that students explained their research to members of their professional and personal communities. Discussions with professional communities largely focused on guidance related to the technical aspects of their research projects and personal communities focused on personal support. We also examined student research project performance and science identity. Bootstrapped multivariate linear modeling indicated that neither student demographic factors nor the degree to which a student discussed their research with their personal or professional communities influenced their research project grades. However, the strength of the professional but not personal connections was associated with science identity. Based on these findings, we offer evidence‐based recommendations to field course instructors on how best to structure student interaction.