The authors report 4 children and adolescents who had the acute onset of a movement and psychiatric disorder after a febrile illness. The differential diagnosis includes poststreptococcal syndromes (Sydenham chorea, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection [PANDAS], acute disseminated encephalomyelitis) and other postinfectious conditions. Their cases illustrate difficulties in making an accurate diagnosis and determining proper therapy and they recommend a standard diagnostic approach. More research is needed to clarify the nature, causes, and appropriate treatment of these types of disorders.