This chapter explains the rationale for developing a reliable and valid client-centred measure of empathy. It discusses the development of a new client-centred empathy scale. The chapter also discusses the features of the new scale. It describes the evaluation of the new measuring scale for reliability and validity, and the results of these investigations. The chapter shows that there was a need for a measure of empathy that measures what nurses ought to be doing during their relationships with clients; clients' perceptions of the helping relationship are a rich source of information about the application of empathy to clinical nursing. It also shows there was a need to develop a measure of nurses' ability to offer empathy that yields consistent results among measures (reliability) and does measure what it is intended to measure (validity).