This article is based on the Department of Health's (England) funded pluralistic evaluation of Nurse Practitioner preparation, 'Realizing Specialist & Advanced Nursing Practice: establishing the parameters of and identifying competencies for "Nurse Practitioner" roles and evaluating programmes of preparation' (RSANP). During this 27-month project, which began in 1996, one of the research methods used, the Delphi study, was aimed at reaching a consensus of views amongst nurses in clinical practice, educators, purchasers, providers and representatives of statutory and professional bodies on the parameters and competencies desirable for the Nurse Practitioner role. The agreed competencies were then used as one measure of the appropriateness of various programmes used to prepare Nurse Practitioners. Of the competencies required for the role, the majority are 'nursing' competencies and are the same as those required for the Clinical Nurse Specialist role. However, for both Clinical Nurse Specialists and Nurse Practitioners, these are practised at a 'higher level'. Other competencies needed for the Nurse Practitioner role relate to the knowledge and skills required to assess, diagnose and determine nursing and medical management of a patient and to evaluate that management. Data indicated, however, that even these competencies were being used by some Clinical Nurse Specialists. Final analysis enabled the identification of the two roles with the use of a 'Typology of Named Clinical Nursing Roles'.