A circumscribed concept of professionalism is available to serve as a foundation for next steps in assessing professional behavior. The current array of assessment tools is rich. However, their measurement properties should be strengthened. Accordingly, future research should explore rigorous qualitative techniques; refine quantitative assessments of competence, for example, through OSCEs; and evaluate separate elements of professionalism. It should test the hypothesis that assessment tools will be better if they define professionalism as behaviors expressive of value conflicts, investigate the resolution of these conflicts, and recognize the contextual nature of professional behaviors. Whether measurement tools should be tailored to the stage of a medical career and how the environment can support or sabotage the assessment of professional behavior are central issues. FINAL THOUGHT: Without solid assessment tools, questions about the efficacy of approaches to educating learners about professional behavior will not be effectively answered.