BackgroundInterpersonal and Communication Skills (ICS) and Professionalism milestones are challenging to evaluate during medical training. Paucity in proficiency, direction and validity evidence of assessment tools of these milestones warrants further research. We validated the reliability of the previously-piloted Instrument for Communication skills and Professionalism Assessment (InCoPrA) in medical learners.MethodsThis validity approach was guided by the rigorous Kane’s Framework. Faculty-raters and standardized patients (SPs) used their respective InCoPrA sub-component to assess distinctive domains pertinent to ICS and Professionalism through multiple expert-built simulated-scenarios comparable to usual care. Evaluations included; inter-rater reliability of the faculty total score; the correlation between the total score by the SPs; and the average of the total score by two-faculty members. Participants were surveyed regarding acceptability, realism, and applicability of this experience.ResultsEighty trainees and 25 faculty-raters from five medical residency training sites participated. ICC of the total score between faculty-raters was generally moderate (ICC range 0.44–0.58). There was on average a moderate linear relationship between the SPs and faculty total scores (Pearson correlations range 0.23–0.44). Majority of participants ascertained receiving a meaningful, immediate, and comprehensive patient-faculty feedback.ConclusionsThis work substantiated that InCoPrA was a reliable, standardized, evidence-based, and user-friendly assessment tool for ICS and Professionalism milestones. Validating InCoPrA showed generally-moderate agreeability and high acceptability. Using InCoPrA also promoted engaging all stakeholders in medical education and training–faculty, learners, and SPs—using simulation-media as pathway for comprehensive feedback of milestones growth.