Acute septic arthritis is a condition with the potential for joint destruction, physeal damage, and osteonecrosis, which warrants urgent identification and treatment. The organism most frequently responsible is Staphylococcus aureus; however, our understanding of pathogens continues to evolve as detection methods continue to improve. MRI has improved our ability to detect concurrent infections and is a useful clinical tool where available. The treatment course involves intravenous antibiotics followed by transition to oral antibiotics when clinically appropriate. The recommended surgical treatment of septic arthritis is open arthrotomy with decompression of the joint, irrigation, and debridement and treatment of concurrent infections.