This article reports 13 cases of pneumococcal septic arthritis and reviews another 177 cases reported since 1965. Of 2407 cases of septic arthritis from large series, 156 (6%) were caused by Streptococcus pneumoniae. Mortality was 19% among adults and 0% among children. Pneumococcal bacteremia was the strongest predictor of mortality. At least 1 knee was involved in 56% of adults. Polyarticular disease (36%) and bacteremia (72%) were more common among adults with septic arthritis caused by S. pneumoniae than among adults with other causative organisms. Only 50% of adults with pneumococcal septic arthritis had another focus of pneumococcal infection, such as pneumonia. Functional outcomes were good in 95% of patients. Uncomplicated pneumococcal septic arthritis can be managed with arthrocentesis and 4 weeks of antibiotic therapy; most cases of pneumococcal prosthetic joint infection can be managed without prosthesis removal. A fatal case of septic arthritis caused by a beta-lactam-resistant strain of S. pneumoniae is also presented.