PURPOSE This study examines the group performance trajectories of athletic training and physical therapy students as they engaged in case-based learning experiences over the course of a semester. METHODS We apply Tuckman and Jensen's (1977) model of group development which predicts a non-linear performance trend as groups progress through the stages of forming, storming, norming, performing, and adjourning. We also examine the extent to which performance trajectories differ between interprofessional and uniprofessional groups. RESULTS As predicted, results suggest a significant non-linear trajectory of group performance across case-study trials. Specifically, a significant cubic trajectory was observed, such that group performance was characterized by two inflections points over time. Although we observed raw mean differences in performance ratings between interprofessional and uniprofessional groups, no significant differences were found across trials. We offer some speculative explanations for why this occurred. CONCLUSION Ultimately, our findings provide insight to educators and practitioners regarding why and when groups may need additional support.