Convulsive therapy was introduced to psychiatric practice in 1934. It was widely hailed as an effective treatment for schizophrenia and quickly recognized as equally effective for the affective disorders. Like other somatic treatments, it was replaced by psychotropic drugs introduced in the 1950s and 1960s. But two decades later, ECT was recalled to treat pharmacotherapy-resistant cases. Avid searches to optimize seizure induction and treatment courses, to reduce risks and fears, to broaden the indications for its use, and to understand its mechanism of action followed. Unlike other medical treatments, however, these searches were severely impeded by a vigorous antipsychiatry movement among the public and within the profession. ECT is effective in the treatment of patients with major depression, delusional depression, bipolar disorder, schizophrenia, catatonia, neuroleptic malignant syndrome, and parkinsonism, and this breadth of action is both remarkable and unique. ECT is a safe treatment. No age or systemic condition bars its use. Its major limitations are the high relapse rates and the occasional profound effects on memory and recall that mar its success. Experiments to sustain its benefits with medications and with continuation ECT are underway. Its mode of action remains a mystery and this puzzle is an unappreciated challenge. The full impact of this intervention is yet to be felt.