Objective: Assessments of antibiotic prescribing in ambulatory care have largely focused on viral acute respiratory infections (ARIs). It is unclear whether antibiotic prescribing for bacterial ARIs should also be a target for antibiotic stewardship efforts. In this study, we evaluated antibiotic prescribing for viral and potentially bacterial ARIs in patients seen at emergency departments (EDs) and urgent care centers (UCCs). Design: This retrospective cohort included all ED and UCC visits by patients who were not hospitalized and were seen during weekday, daytime hours during 2016–2018 in the Veterans Health Administration (VHA). Guideline concordance was evaluated for viral ARIs and for 3 potentially bacterial ARIs: acute exacerbation of COPD, pneumonia, and sinusitis. Results: There were 3,182,926 patient visits across 129 sites: 80.7% in EDs and 19.3% in UCCs. Mean patient age was 60.2 years, 89.4% were male, and 65.6% were white. Antibiotics were prescribed during 608,289 (19.1%) visits, including 42.7% with an inappropriate indication. For potentially bacterial ARIs, guideline-concordant management varied across clinicians (median, 36.2%; IQR, 26.0–52.7) and sites (median, 38.2%; IQR, 31.7–49.4). For viral ARIs, guideline-concordant management also varied across clinicians (median, 46.2%; IQR, 24.1–68.6) and sites (median, 40.0%; IQR, 30.4–59.3). At the clinician and site levels, we detected weak correlations between guideline-concordant management for viral ARIs and potentially bacterial ARIs: clinicians (r = 0.35; P = .0001) and sites (r = 0.44; P < .0001). Conclusions: Our findings suggest that, across EDs and UCCs within VHA, there are major opportunities to improve management of both viral and potentially bacterial ARIs. Some clinicians and sites are more frequently adhering to ARI guideline recommendations on antibiotic use.