OBJECTIVE To reduce inappropriate antimicrobial prescribing across ambulatory care, understanding the patient-, provider-, and practice-level characteristics associated with antibiotic prescribing is essential. In this study, we aimed to elucidate factors associated with inappropriate antimicrobial prescribing across urgent care, family medicine, and pediatric and internal medicine ambulatory practices. DESIGN, SETTING, AND PARTICIPANTS Data for this retrospective cohort study were collected from outpatient visits for common upper respiratory conditions that should not require antibiotics. The cohort included 448,990 visits between January 2014 and May 2016. Carolinas HealthCare System urgent care, family medicine, internal medicine and pediatric practices were included across 898 providers and 246 practices. METHODS Prescribing rates were reported per 1,000 visits. Indications were defined using the International Classification of Disease, Ninth and Tenth Revisions, Clinical Modification (ICD-9/10-CM) criteria. In multivariable models, the risk of receiving an antibiotic prescription was reported with adjustment for practice, provider, and patient characteristics. RESULTS The overall prescribing rate in the study cohort was 407 per 1,000 visits (95% confidence interval [CI], 405-408). After adjustment, adult patients seen by an advanced practice practitioner were 15% more likely to receive an antimicrobial than those seen by a physician provider (incident risk ratio [IRR], 1.15; 95% CI, 1.03-1.29). In the pediatric sample, older providers were 4 times more likely to prescribe an antimicrobial than providers aged ≤30 years (IRR, 4.21; 95% CI, 2.96-5.97). CONCLUSIONS Our results suggest that patient, practice, and provider characteristics are associated with inappropriate antimicrobial prescribing. Future research should target antibiotic stewardship programs to specific patient and provider populations to reduce inappropriate prescribing compared to a "one size fits all" approach. Infect Control Hosp Epidemiol 2018;39:307-315.