This study, conducted by the CDC EPIC Study Team, aimed to estimate the incidence of community-acquired pneumonia (CAP) requiring hospitalization among U.S. adults and to identify the pathogens responsible for these infections. The study was conducted in five hospitals in Chicago and Nashville from January 2010 to June 2012. Active population-based surveillance was used, and patients were excluded if they had recently been hospitalized or had severe immunosuppression. Blood, urine, and respiratory specimens were collected for various diagnostic tests, and chest radiographs were independently reviewed by radiologists. The study found that among 2,320 adults with radiographic evidence of pneumonia, the median age was 57 years, and the median length of hospital stay was 3 days. Pathogens were detected in 853 (38%) of these patients, with viruses detected in 23% and bacteria in 11%. The most common pathogens were human rhinovirus (9%), influenza virus (6%), and *Streptococcus pneumoniae* (5%). The annual incidence of CAP requiring hospitalization was 24.8 cases per 10,000 adults, with the highest rates among adults aged 65 to 79 years (63.0 cases per 10,000 adults) and those 80 years or older (164.3 cases per 10,000 adults). The study highlights the substantial burden of CAP among adults, particularly the oldest age groups, and suggests the need for improved diagnostic methods and targeted interventions to reduce the burden of this infection.This study, conducted by the CDC EPIC Study Team, aimed to estimate the incidence of community-acquired pneumonia (CAP) requiring hospitalization among U.S. adults and to identify the pathogens responsible for these infections. The study was conducted in five hospitals in Chicago and Nashville from January 2010 to June 2012. Active population-based surveillance was used, and patients were excluded if they had recently been hospitalized or had severe immunosuppression. Blood, urine, and respiratory specimens were collected for various diagnostic tests, and chest radiographs were independently reviewed by radiologists. The study found that among 2,320 adults with radiographic evidence of pneumonia, the median age was 57 years, and the median length of hospital stay was 3 days. Pathogens were detected in 853 (38%) of these patients, with viruses detected in 23% and bacteria in 11%. The most common pathogens were human rhinovirus (9%), influenza virus (6%), and *Streptococcus pneumoniae* (5%). The annual incidence of CAP requiring hospitalization was 24.8 cases per 10,000 adults, with the highest rates among adults aged 65 to 79 years (63.0 cases per 10,000 adults) and those 80 years or older (164.3 cases per 10,000 adults). The study highlights the substantial burden of CAP among adults, particularly the oldest age groups, and suggests the need for improved diagnostic methods and targeted interventions to reduce the burden of this infection.