Children 60 days–18 years of age that were discharged from one of the participating hospitals between January 1, 2010 and December 31, 2010, with at least one ICD-9-CM discharge diagnosis code (primary or any secondary) indicating pneumonia, pleural effusion, or empyema (n=5023) were considered for inclusion. [Figure 1.] Two investigators independently reviewed concomitant ICD-9-CM codes for each hospitalization (up to 21 codes), excluding patients with diagnoses that precluded CAP (e.g. cystic fibrosis or immunodeficiency) (n=1,377). A 25% random sample of the remaining 3,646 discharges was then selected for medical record review (n=998). To identify potential missed pneumonia cases, discharges without an ICD-9-CM pneumonia-related diagnosis code (matched by date of admission to account for seasonal trends in pneumonia admissions) were also selected for medical record review (n=1000).