Poststreptococcal reactive arthritis (PSRA) is associated with prior group A β-hemolytic streptococcal infection and has a reported annual incidence of 1 to 2 cases per 100,000 persons, approximately twice that of acute rheumatic fever (ARF) in the US. Children who present with reactive arthritis are not uncommon in a busy general pediatric practice in the US, whereas children who present with ARF are very rare. Distinguishing PSRA from ARF can be challenging because the symptoms and signs are similar, but the diseases differ in long-term therapy, follow-up evaluation, and prognosis. We review the diagnostic criteria for PSRA, the pertinent features of the 2015 ARF diagnostic guideline from the American Heart Association, and the major characteristics that differentiate PSRA from ARF.