Community acquired pneumonia (CAP) is a serious illness, in which the etiology of disease cannot be determined in 50% of the patients. The American Thoracic Society (ATS) and the Infectious Disease Society of America (IDSA) have independently developed treatment guidelines for CAP. These guidelines, however, differ in their approaches. The differences can be attributed to their unique approaches. ATS favors the application of empiric methodology verse IDSA, which recommends a definitive clinical approach. Presently, a widely accepted, standardized guideline for the diagnosis and treatment of CAP is unavailable. This contributes to the large variation in admission rates, use of institutional resources, and quality of care given to CAP patients.