Study objectives: To compare process of care performance, patient characteristics, and outcomes in a contemporary cohort of elderly (greater than or equal to 65 years) patients hospitalized with community-acquired pneumonia (CAP) or with nursing home-acquired pneumonia (NHAP), Design: State-nide retrospective cohort study. Setting: Thirty-four acute-care hospitals in Connecticut. Patients: Elderly Medicare patients hospitalized in 1995-1996 with CAP (1,131) or with NHAP (528), Measurements: Antibiotic administration within 8 h of hospital arrival, blood culture collection within 24 h of hospital arrival, oxygenation assessment within 24 h of hospital arrival, demographic and clinical characteristics, in-hospital complications, mortality, and length of stay. Results: Process of care performance rates for patients with CAP and NHAP were equivalent for antibiotic administration within 8 h of hospital arrival (76.8% vs 76,3%, respectively; p = 0.82), blood culture collection within 24 h of hospital arrival (78.1% vs 81.1%, respectively; p = 0.31), and oxygenation assessment within 24 h of hospital arrival (94.7% vs 95.3%, respectively; p = 0.70), Patients with CAP were younger than those with NHAP (median age, 80 vs 84 years, respectively p < 0,001), had less cerebrovascular disease (16.8% vs 34.7%, respectively; p less than or equal to 0,001), and lower mortality risk scores at hospital presentation (median, 100 vs 137, respectively; p less than or equal to 0.001) than patients with NHAP, The median length of stay was equivalent (7 clays), but the in-hospital mortality rate was lower in patients with CAP than in patients with NHAP (8.0% vs 18.6%, respectively; p less than or equal to 0,001), Conclusion: initial hospital processes of care are performed at the same rate in patients hospitalized,vith CAP or NHAP. However, patients with CAP are younger, are less acutely and chronically ill, and have lower in-hospital mortality rates than patients with NHAP.