Clinical practice guidelines have a long and distinguished tradition in pediatrics. Currently, the American Academy of Pediatrics has developed more than 15 practice guidelines and more than 250 clinical policy statements. In the past, practice guidelines have been used to improve care through the dissemination of evidence-based, clinically effective practices to pediatric practitioners. In the current environment this purpose has been broadened to include cost reduction, standardization of practice, and reduction of medical liability. This has led to both confusion and distrust on the part of the pediatrician. Practice guidelines are best understood as a tool to insure that children receive evidence-based care. They are best used in association with a set of outcome and performance measures that provide feedback to clinicians and allow for modification of the guidelines to meet the needs of the local patient population. The quality of practice guidelines is directly dependent on the quality of the medical evidence supporting the recommendation. Unfortunately only a small percentage of the evidence supporting practice guidelines comes from randomized clinical trials with the majority of the evidence coming from expert clinical panels. The success of practice guidelines in improving care for children has yet to be convincingly demonstrated. Currently, there is a dearth of well designed studies that document the effectiveness of practice guidelines. Their ultimate effectiveness will depend on both an improved evidence base and effective strategies for rapid dissemination of the recommendations. The development of evidence-based practice guidelines does not insure that it will have a major impact on physician practice. In the past, effective dissemination of new knowledge has been a long process, often taking years. This cycle time can be dramatically shortened through the development of networks of practice sites that share knowledge and experience in the implementation of practice guidelines and the use of strategies that take advantage of key groups in the dissemination process. When used appropriately, practice guidelines can provide an important adjunct to clinical research by facilitating the dissemination of new clinical findings and can provide an important platform for encouraging innovations in patient care.