Many patients with CAP are seen in the ER and treated as outpatients.History, physical examination, selected lab tests, and chest radiography must be routinely undertaken in patients with "presumptive" pneumonia to make the diagnosis and allow for appropriate risk stratification. There is wide disagreement among physicians on the presence or absence of CAP on chest radiographs, and a chest radiograph that shows "no pneumonia" may not be sufficient to rule out the diagnosis. Furthermore, even patients with "ambulatory" pneumonia may have important laboratory abnormalities and a moderate risk of hypoxemia. Diabetes mellitus and stress hyper-glycemia are important comorbidities and must be accounted for in any rational discharge plan. All of the aforementioned observations need to be understood in the context of an increasingly older and frailer patient population that may still be eligible for appropriate outpatient treatment. It is likely that guidelines and clinical pathways for outpatient treatment of CAP that standardize medical care and mandate careful and regular follow-up of patients discharged home will decrease unnecessary practice variation while improving the overall quality of care.