We hypothesize that implementation of a clinician decision support system, with an active education component, will reduce the inappropriate use of antibiotics in primary care office practices. Our hypothesis is based on the premise that most inappropriate prescribing is the result of multiple factors that include difficulty in distinguishing a benign, self-limited viral infection from a more serious bacterial infection; overdiagnosis of a bacterial infection in cases where there is clinical uncertainty as to the true nature of the illness; and constraints on the time available for clinicians to explain to patients the nature of the illness and the reasons an antibiotic is not indicated.