BACKGROUND Interprofessional (IP) socialization is important to develop early in the training of health professions students. OBJECTIVE This study compared changes in health professions students' IP socialization and readiness to function in IP teams and sought to understand students' participation experiences using a simulation learning game ( Friday Night at the ER [FNER]). METHODS The single-center study targeted students in 13 health professions programs using a mixed-methods design. Student teams engaged in open discussion, played the game, and participated in team debriefing. RESULTS IP socialization increased from fairly great to great extent among all students. Qualitative analyses revealed 3 overarching themes supporting the development of IP communication and systems-based thinking. Program evaluation data revealed that students highly valued this experience as being effective and important to their professional development. CONCLUSIONS An IP experience consisting of FNER gameplay and structured debriefing can improve IP socialization and lay the foundation for the development of IP skills among early health professions students.