The population of adults with congenital heart disease (ACHD) now exceeds that of children with congenital heart disease. Within this relatively young population of adults in their third decade of life exist a population of patients with heart failure (HF) who, in functional status, closely resemble patients in their fifth and sixth decades of life with HF caused by coronary artery disease and myocardial ischemia. The ACHD patients currently at greatest risk for HF are those with single-ventricle physiology, those with a 2-ventricle circulation with the right ventricle as the systemic ventricle, and those with repaired tetralogy of Fallot and pulmonary valve insufficiency. This article will review the demographics, diagnosis, functional capacity, and treatment of HF in the ACHD population.