We propose to conduct a randomized controlled trial of a quality improvement program consisting of physician education (educational seminar, practice guidelines, performance feedback, and decision support tools) and patient education (waiting room print and audiovisual materials) in 8 VA hospital and 8 non-VA hospital emergency departments. Non VA study sites will be identified from an existing research network of hospital emergency departments--EDNet. VA hospital sites will be selected among academically affiliated hub facilities. Phase one will involve a hospital-level randomized trial of a multidimensional intervention to translate existing evidence based guidelines for antibiotic use in ARIs vs. usual care. Simultaneously, we will validate a new CRP-based diagnostic algorithm and incorporate it into the evidence based guidelines for antibiotic use in ARIs. Phase two will involve a second hospital-level randomized trial of the new antibiotic use guidelines that incorporate the CRP-based diagnostic algorithm vs. the original guidelines. Specific endpoints include the overall success of the intervention in each phase in terms of reducing antibiotic prescribing for ARIs, improving patient outcomes and reducing resource utilization. In addition we will examin the impact of VA and non-VA organizational factors on the successful translation of various components of the intervention in both phases. Data will be collected using existing administrative data as well as on-site enrollment of subjects in prospective follow-up studies.