In an acute inpatient environment, clinicians are often faced with patients experiencing mental illness to an extent that is life-threatening, whether this is through absolute loss of the will to eat and drink, through the intense impulse towards suicide, or through the sheer exhaustion of severe mania. It is essential to have the ability to bring these symptoms under control in a way that is rapid, effective, and humane, and electroconvulsive therapy (ECT) provides this. Despite enormous advances in the safe delivery, regulation, and efficacy of ECT over the last 70 years, and its ability to bring patients from stupor to recovery over (on average) just 6–12 treatments, it remains a stigmatized and stigmatizing treatment in the public eye. This chapter outlines the history of ECT, and explains how it can be safely prescribed and monitored, and who will be most likely to benefit.