Physicians' interpersonal and communication skills have a significant impact on patient care and correlate with improved healthcare outcomes. Some studies suggest, however, that communication skills decline during the four years of medical school. Regulatory and other medical organizations, recognizing the importance of interpersonal and communication skills in the practice of medicine, now require competence in communication skills. Two challenges exist: to select a framework of interpersonal and communication skills to teach across undergraduate medical education, and to develop and implement a uniform model for the assessment of these skills. The authors describe a process and model for developing and institutionalizing the assessment of communication skills across the undergraduate curriculum. Consensus was built regarding communication skill competencies by working with course leaders and examination directors, a uniform framework of competencies was selected to both teach and assess communication skills, and the framework was implemented across the Harvard Medical School undergraduate curriculum. The authors adapted an assessment framework based on the Bayer-Fetzer Kalamazoo Consensus Statement adapted a patient and added and satisfaction tool to bring patients' perspectives into the assessment of the learners. The core communication competencies and evaluation instruments were implemented in school-wide courses and assessment exercises including the first-year Patient-Doctor I Clinical Assessment, second-year Objective Structured Clinical Exam (OSCE), third-year Patient-Doctor III Clinical Assessment, fourth-year Comprehensive Clinical Practice Examination and the Core Medicine Clerkships. Faculty were offered workshops and interactive web-based teaching to become familiar with the framework, and students used the framework with repeated opportunities for faculty feedback on these skills. A model is offered for educational leaders and others who are involved in designing assessment in communication skills. By presenting an approach for implementation, the authors hope to provide guidance for the successful integration of communication skills assessment in undergraduate medical education.