Autoimmune dementia and encephalopathy represent an exciting and rapidly evolving field of “treatable” and “potentially reversible” neurological disorders. Clues helpful in identifying patients with an autoimmune dementia include (i) subacute onset, rapidly progressive course, and fluctuating symptoms, (ii) the detection of CSF or serological biomarkers of autoimmunity (such as neural autoantibodies), and (iii) a response to immunotherapy. Resolution or improvements in neuropsychological, EEG, MRI, or functional imaging abnormalities after immunotherapy provide objective evidence of immunotherapy responsiveness. Objective improvements (resulting in meaningful functional gains) after an initial trial of immunotherapy should prompt consideration of longer-term maintenance immunotherapy (combination of slowly tapered infusions of corticosteroids or IVIG and an oral immunosuppressant) to maintain remission. Controlled studies are needed to determine the optimum treatments and duration of therapy.