Implantable cardioverter-defibrillators (ICDs) reduce sudden cardiac death (SCD) and improve survival in patients with a history of life-threatening arrhythmia or sudden cardiac arrest, and in select populations at high risk of SCD due to ventricular arrhythmias. However, patients with ICDs may receive inappropriate or unnecessary shocks, which have been associated with pro-arrhythmia, psychological sequelae, poor quality of life, and increased mortality. The benefits and risks of ICD therapy are therefore directly impacted on by physician operative and programming decisions. This article aims to provide a detailed review of transvenous ICD programming as guided by clinical trials.