Integrating newcomers and fostering collaboration between researchers with different disciplinary backgrounds is a challenge for scientific communities. Prior research suggests that both network-driven selection patterns (reciprocity and transitivity) and the active selection of specific others are important. Selecting appropriate collaboration partners may moreover require what we call cognitive group awareness, (i.e. knowledge about the knowledge of others). In a field study at two multidisciplinary scientific events (Alpine RendezVous 2011 and 2013) including N= 287 researchers, we investigated selection patterns, looking specifically at career level and disciplinary background, and included a cognitive group awareness intervention. While we could not completely explain how researchers choose with whom they interact, we found that transitivity and interaction duration are relevant for later collaboration. Cognitive group awareness support was beneficial for fostering interdisciplinary collaboration. Career level was a less relevant factor. We discuss measures for supporting newcomer integration and community buildings based on our findings.