A common assumption in higher education is that international students find it difficult to develop learning and friendship relations with host students. When students are placed in a student-centred environment, international students from different cultural backgrounds are "forced" to work together with other students, which allows students to learn from different perspectives. However, large lecture rooms may provide fewer opportunities for students to work together in small groups. The purpose of this article is to understand how 191 international students from 34 cultural backgrounds and 16 host students build learning and friendship relations in a large classroom of 207 students. We have used an innovative mixed-method design of social network analysis in a pre- and post-test manner combined with two sets of focus groups. Using multiple regression quadratic assignment procedures, the results indicate that learning ties after 11 weeks were significantly predicted by the friendship and learning ties established at the beginning of the module, (sub)specialisation, and whether students were Chinese or not. Contrary to previous findings, team divisions played only a marginal role in building (new) learning relations. A substantial segregation between Confucian Asian, European international and UK students was present. Follow-up qualitative data highlighted that international students made a conscious effort to build friendship and learning relations primarily outside the formal team, which for some were along co-national lines, while others were pro-actively looking for new perspectives from multi-national students. These results indicate that the instructional design might have a strong influence on how international and host students work and learn together. We believe that this study is the first to provide an in-depth and unique understanding of how international students from different cultural backgrounds build friendship and learning-relationships with other students in- and outside their classroom over time in a large classroom of 200+ students.