We compare case-mix, hospitalization rates, length of stay (LOS), and resource use in independent freestanding emergency departments (FSEDs) and hospital-based emergency departments (H-EDs).Data from 74 FSEDs (2013-5) in Texas and Colorado, were compared to H-ED data from the 2013-14 National Hospital Ambulatory Medical Care Survey. In the unrestricted sample, large differences in visit characteristics (e.g. payer and case mix) were found between patients that use FSEDs compared to H-EDs. Therefore, we restricted our analysis to patients commonly treated in both settings (<65 years, privately insured, non-ambulance) and used inverse propensity score weighting (IPW) to balance the two settings on observable patient characteristics. We then compared ED length of stay and as well as hospital admission rates and resource utilization rates in the IPW-weighted samples.Before balancing, FSEDs saw more young adults (age 25-44), and fewer older adults (age 45-64) than H-EDs. FSED patients had fewer comorbidities, more injuries and respiratory infections, and fewer diagnoses of chest or abdominal pain. In balanced samples, LOS for FSED visits was 46% shorter (60 minutes) than H-ED patients. Hospital admission rates were 37% lower overall (95% CI -51%, -23%) in FSEDs and varied considerably by primary discharge diagnosis. X-ray and EKG use was significantly lower at FSEDs while others measures of resource utilization were similar (ultrasound, CT scans and laboratory tests).In this sample of FSEDs, a greater proportion of younger patients with fewer comorbidities and more injuries and respiratory system diseases were evaluated, and almost all patients had private health insurance. When restricted to <65, privately insured, and non-ambulance patients in both samples, LOS was considerably shorter and hospital admission rates lower at FSEDs, as well as the use of some diagnostic testing. This study is limited as diagnoses codes may not fully capture severity and patients who perceived greater need of hospital admission may have chosen a H-ED over FSEDs. This article is protected by copyright. All rights reserved.