An attempt was made to introduce an innovation (nurse practitioners) into an organization (an outpatient clinic) using the format of a clinical trial. Staff physicians evaluated patients as to their acceptability for care by nurse practitioners before and after a 12-month trial. "Acceptable" patients were randomly assigned to control (regular clinic) and experimental groups (nurse practitioner care). There was a statistically significant increase (p less than 0.001) in physicians' willingness to delegate patients to nurse practitioners for care after the trial. Initial assessments of "acceptable" were highly associated with demographic variables such as age, race, and level of education. Patients' medical status, rather than personal characteristics, were found to be associated with decision making on re-evaluation. Positions were created for nurse practitioners on the staff of the clinic at the end of the experiment.