Defining quality patient care is a complex and often confusing issue. This article describes one hospital's experience in applying quality improvement theories to inpatient clinical nutrition practice. The key to measuring quality was the use of standardized practice guidelines. In this article, terms such as continuous quality improvement are clarified and fundamental assumptions such as ''quality is defined as conformance to requirements'' are discussed. We review a working model for the 10-step plan of the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) and its application in practice, including the indicators and measurement tools used. Actual results from ongoing quality improvement efforts are addressed and compared to the JCAHO nine components of quality patient care. Because of preexisting nutrition practice guidelines at the Yale-New Haven Hospital, improvements in the delivery of patient nutrition care could be demonstrated; these included enhanced efficiencies in screening and intervention. Continuous quality improvement initiatives do work, and practitioners can use the practice experience presented here as a conceptual framework to justify or validate the quality of patient nutrition care in their own institutions. J Am Diet Assoc. 1995; 95:65-74.