Cardiomyopathies represent a heterogeneous group of heart muscle diseases that are a major cause of morbidity and mortality (Watkins et al., N Engl J Med 364(17):1643–1656, 2011; McMurray, N Engl J Med 362(3):228–238, 2010). Classification schemes for cardiomyopathy have been complex, and efforts have been made to classify the disease states based on myocardial characteristics and etiologies (Maron et al., Circulation 113:1807–1816, 2006). The etiology, diagnosis, and management of dilated cardiomyopathy (DCM), restrictive/infiltrative cardiomyopathy, and hypertrophic cardiomyopathy (HCM) are the subject of this chapter and several features of each form of cardiomyopathy are highlighted in Table 1.