Background: Effective interprofessional collaboration (IPC) has been shown to depend on clear role definitions, yet there are important gaps with regard to role clarity in the IPC literature. The goal of this study was to evaluate whether there was a relationship between internal medicine residents' and nurses' role perceptions and their actual actions in practice, and to identify areas that would benefit from more specific interprofessional education. Methods: Fourteen residents and 14 nurses working in internal medicine were interviewed about their role perceptions, and then randomly paired to manage two simulated clinical cases. The authors adopted a general inductive approach to analyze the interviews. They identified 13 different role components that were then compared to data from simulations. Descriptive and kappa statistics were used to assess whether there was a relationship between role components identified in interviews and those performed in simulations. Results from these analyses guided a further qualitative evaluation of the relationship between role perceptions and actions. Results: Across all 13 role components, there was an overall statistically significant, although modest, relationship between role perceptions and actions. In spite of this relationship, discrepancies were observed between role components mentioned in interviews and actions performed in simulations. Some were more frequently performed than mentioned (e.g. “Having common goals”) while others were mentioned but performed only weakly (e.g. “Providing feedback”). Conclusions: Role components for which perceptions do not match actions point to role ambiguities that need to be addressed in interprofessional education. These results suggest that educators need to raise residents' and nurses' awareness of the flexibility required to work in the clinical setting with regard to role boundaries.