Words do not of themselves carry meaning but are interpreted by users and within the contexts of their use. These contexts extend beyond the immediate to include historical, contemporary and evolving uses. Particularly within interpersonal communication, shared meanings and therefore understandings are often negotiated. This theory of language applies both to the phrase ‘informed consent’ and to the sharing of information that is believed to be an integral part of informed consent. The notion labelled ‘informed consent’ in New Zealand society today occurs within individuals’ understandings of the phrase, and the philosophical, legal, official, scholarly and popular expressions of understandings that are publicly articulated through various media. Active and adequate recognition of the rights of consumers of New Zealand’s health and disability services, including those that hospitals provide, rests on a shared understanding of ‘informed consent’. This understanding, which constitutes what is called a concept, may be arrived at through careful consideration of a wide range of interpretations associated with this phrase. Such a consideration makes up the content of this thesis.