Effective communication between doctor and patient is a core clinical skill. It is increasingly recognized that it should and can be taught with the same rigour as other basic medical sciences. To validate this teaching, it is important to define the content of communication training programmes by stating clearly what is to be learnt. We therefore describe a practical teaching tool, the Calgary-Cambridge Referenced Observation Guides, that delineates and structures the skills which aid doctor-patient communication. We provide detailed references to substantiate the research and theoretical basis of these individual skills. The guides form the foundation of a sound communication curriculum and are offered as a starting point for programme directors, facilitators and learners at all levels. We describe how these guides can also be used on an everyday basis to help facilitators teach and students learn within the experiential methodology that has been shown to be central to communication training. The learner-centred and opportunistic approach used in communication teaching makes it difficult for learners to piece together their evolving understanding of communication. The guides give practical help in countering this problem by providing: an easily accessible aide-mémoire; a recording instrument that makes feedback more systematic; and an overall conceptual framework within which to organize the numerous skills that are discovered one by one as the communication curriculum unfolds.