For as long as many libraries have charged fines for books returned after their due dates, this familiar practice has excited comment and controversy. Fines are thought by many to deter patrons from keeping materials too long. However, others believe there is little persuasive evidence that fines are more effective at minimizing overdues than are reminder notices. Further, some critics contend charging fines is unethical, especially in public or school libraries, and the meager results are not worth the harmful public relations fines incur. The authors experimented with an alternative approach using positive reinforcement.