Patients want empathetic physicians who listen and understand. How do you teach and measure empathy? Medical educators, including those inspired by Alan Alda, have turned to theater to teach skills in empathetic communication. Improvisation-informedcurriculum (medical improv) draws upon foundational actors training: deep listening, emotional understanding, connections, authenticity. Arating scale to measure the impact of medical improv on empathetic and clear communication does not exist. : To develop aframework and instrument, the Empathy and Clarity Rating Scale (ECRS), for measuring communication elements used by actors and physicians, and pilot ECRS to test effectiveness of medical improv on first-yearstudents' communication skills. : Four medical schools collaborated. USMLE Step 2 Communication and Interpersonal Skills (CIS) domains were used as framework for discussion among three focus groups, each with clinicians, actors, communication experts, and community members with patient experience. Audiotaped discussions were transcribed; open coding procedures located emerging themes. The initial coding scheme was compared with the Consultation and Relational Empathy (CARE) measure. ECRS content was aligned with CARE, CIS and focus group themes. Modified nominal processes were conducted to finalize the scale. We implemented procedures to establish content validity and interrater reliability. Final ECRS was used to study student performance across three levels of experience with medical improv. : The final ECRS was comprised of seven five-pointscale items. Narrative comments precede behaviorally anchored ratings: 5=desired, 1=ineffective, 2-4=developing based upon adjustment needed. Rater agreement across all items was 84%. There was asmall correlation between the ECRS and another measure interviewing (r=0.262, p=0.003). Students with advanced medical improv training outperformed those without (F=3.51, p=.042). : Acommunication scale enlightened by experiences of actors, clinicians, scholars and patients has been developed. The ECRS has potential to detect the impact of medical improv on development of empathetic and clear communication.