Anti-N-methyl-D-aspartate receptor (NMDA) encephalitis is an underrecognized encephalitis that may be mistaken for a wide variety of mental illnesses and causes of delirium. This syndrome is predominantly present in young females presenting with acute psychotic episodes, autonomic instability, and neurologic abnormalities. It is commonly associated with ovarian teratoma. Our case illustrates anti-NMDA encephalitis presenting in a young female with progressive mental status changes and neurologic abnormalities throughout her emergency department course. We review the investigative approach, diagnostic modalities, and treatment options in patient management. This case emphasizes the need for a high index of suspicion of anti-NMDA receptor encephalitis when approaching a patient with unexplained changes in mentation.