Collaborative practice is essential for supporting students with additional needs in schools and often requires working across multiple disciplines. We explored the collaborative interactions of two professions in an interdisciplinary problem-solving task. Teacher candidates and speech pathology students were audio and video recorded working through a structured case study together in small groups. Survey data elicited perceptions of the learning experience. Collaborative argumentation (proposing a claim, giving examples and evidence, and stating a position) was key to problem-solving, alongside seeking clarification and explaining. Specific, realistic experiences in interdisciplinary argumentation like this may support future professional collaborative practice.