Summary Background Mortality from severe sepsis and septic shock differs across continents, countries, and regions. We aimed to use data from the Surviving Sepsis Campaign (SSC) to compare models of care and outcomes for patients with severe sepsis and septic shock in the USA and Europe. Methods The SSC was introduced into more than 200 sites in Europe and the USA. All patients identified with severe sepsis and septic shock in emergency departments or hospital wards and admitted to intensive care units (ICUs), and those with sepsis in ICUs were entered into the SSC database. Patients entered into the database from its launch in January, 2005, through January, 2010, in units with at least 20 patients and 3 months of enrolment of patients were included in this analysis. Patients included in the cohort were limited to those entered in the first 4 years at every site. We used random-effects logistic regression to estimate the hospital mortality odds ratio (OR) for Europe relative to the USA. We used random-effects linear regression to find the relation between lengths of stay in hospital and ICU and geographic region. Findings 25 375 patients were included in the cohort. The USA included 107 sites with 18 766 (74%) patients, and Europe included 79 hospital sites with 6609 (26%) patients. In the USA, 12 218 (65·1%) were admitted to the ICU from the emergency department whereas in Europe, 3405 (51·5%) were admitted from the wards. The median stay on the hospital wards before ICU admission was longer in Europe than in the USA (1·0 vs 0·1 days, difference 0·9, 95% CI 0·8–0·9). Raw hospital mortality was higher in Europe than in the USA (41·1% vs 28·3%, difference 12·8, 95% CI 11·5–14·7). The median length of stay in ICU (7·8 vs 4·2 days, 3·6, 3·3–3·7) and hospital (22·8 vs 10·5 days, 12·3, 11·9–12·8) was longer in Europe than in the USA. Adjusted mortality in Europe was not significantly higher than that in the USA (32·3% vs 31·3%, 1·0, −1·7 to 3·7, p=0·468). Complete compliance with all applicable elements of the sepsis resuscitation bundle was higher in the USA than in Europe (21·6% vs 18·4%, 3·2, 2·2–4·4). Interpretation The significant difference in unadjusted mortality and the fact that this difference disappears with severity adjustment raise important questions about the effect of the approach to critical care in Europe compared with that in the USA. The effect of ICU bed availability on outcomes in patients with severe sepsis and septic shock requires further investigation. Funding Eli Lilly Co, Baxter Lifesciences, Philips Medical Systems, the Society of Critical Care Medicine, and the European Society of Intensive Care Medicine.