Chronic heart failure in pediatric patients is a constellation of symptoms that represent poor cardiac output and, subsequently, multisystem organ involvement. The etiology is broad and includes congenital heart disease, infectious or acquired cardiomyopathies, disorders of metabolism, malformation syndromes, and systemic illnesses. Additionally, it can be further characterized by the ejection fraction of the systemic ventricle (reduced or preserved), by left- or right-heart dysfunction, or by low cardiac output vs congestive heart failure. Diagnosis relies on a constellation of signs and symptoms, physical exam, and testing, including electrocardiogram, imaging, invasive hemodynamics, and circulating biomarkers. Therapeutic options rely heavily on etiology and symptoms, and may range from periodic monitoring to oral therapies to advanced therapies, such as continuous inotrope infusion, mechanical circulatory support, or heart transplantation. Overall, outcomes have significantly improved over the last several decades, but much work remains.