There is a reciprocal relationship between conceptual models of nursing and nursing practice. Conceptual models influence clinical nursing practice by specifying standards for and purposes of practice; identifying relevant clinical problems, settings for practice, legitimate recipients of nursing care, and the content for the nursing process; suggesting methods for delivery of nursing services; and by providing frameworks for clinical information systems, patient classifications systems and quality assurance programmes. Nursing practice, in turn, provides data that can be used to determine the credibility of the conceptual models. Sources of data from clinical practice for credibility determination include evaluations of nursing interventions, the recipient's perspective of nursing care and quality assurance reviews.