This AMEE Guide in Medical Education is Part 1 of a two part Guide covering the issues of Communication. This Guide has been written to provide guidance for those involved in planning the assessment of clinical communication and provides guidance and information relating to the assessment of various aspects of clinical communication; its underlying theory; its practical ability to show that an individual is competent and its relationship to students' daily performance. The advantages and disadvantages of assessing specific aspects of communication are also discussed. The Guide draws attention to the complexity of assessing the ability to communicate with patients and healthcare professionals, with issues of reliability and validity being highlighted for each aspect. Current debates within the area of clinical communication teaching are raised: when should the assessment of clinical communication occur in undergraduate medical education?; should clinical communication assessment be integrated with clinical skills assessment, or should the two be separate?; how important should the assessment of clinical communication be, and the question of possible failure of students if they are judged not competent in communication skills? It is the aim of the authors not only to provide a useful reference for those starting to develop their assessment processes, but also provide an opportunity for review and debate amongst those who already assess clinical communication within their curricula, and a resource for those who have a general interest in medical education who wish to learn more about communication skills assessment.