Arrhythmogenic right ventricular cardiomyopathy (ARVC) originally emerged as a pathologic diagnosis based on distinctive autopsy findings in cases of premature sudden death. Subsequently these characteristic pathologic features were associated with ventricular tachycardia of right ventricular origin and syncope. ARVC is a rare condition and our understanding of the disorder has been confounded by multiple small, highly selected series. Driven by both family studies and improved non-invasive imaging tools the clinical diagnosis of ARVC has broadened, in some instances extending far beyond the original limits of the syndrome. In recent years false-positive diagnoses have increased, thus stimulating investigators to move toward more rigorous clinical criteria. Despite the efforts of a Task Force to establish a baseline for subsequent empiric testing, these criteria have often inadvertently been used as a definitive diagnostic tool in the absence of prospective data. Recent genetic studies have revealed substantial etiologic heterogeneity, and ARVC is emerging as a syndrome consisting of multiple discrete disease entities, in part explaining the tremendous variation in clinical features and natural history seen in prior reports.