The incidence of and risk factors for community-acquired pneumonia (CAP) are described from 2000 to 2005 in a multicenter US cohort of HIV-infected children. In 736 patients, 87 episodes of CAP (33.2 events/1000 person-years) had a mean CD4% of 23% (controls: 30%) and mean CD4 cell count of 668 cells/μl (controls: 870 cells/μl). CAP incidence decreased 44% from 2000-2001 to 2002-2005. On multivariate analysis, viral load at least 100 000 copies/ml (odds ratio 3.98; confidence interval 1.05-15.13) was associated with CAP. Herd immunity through pneumococcal immunization may have diluted the effect of individual immunization in this cohort.