Nonischemic myocardial disease or cardiomyopathy can present as arrhythmia, palpitations, heart failure, dyspnea, lower extremity edema, ascites, syncope, and/or chest discomfort and can be classified as either systolic, diastolic, or a combination of both. Echocardiography is the mainstay of evaluating left ventricular function. However, cardiac magnetic resonance imaging (MRI) is now considered the reference standard imaging technique to assess myocardial anatomy, function, and viability. Advanced MRI techniques with delayed myocardial enhancement, especially, can provide information beyond echocardiography for tissue characterization in CM and can assist in determining specific etiology or in narrowing the differential. Often imaging enhancement patterns, signal characteristics, and morphology on MRI can lead to specific diagnoses such as amyloidosis, hypertrophic CM, or iron deposition. Cardiac computed tomography is usually used in excluding coronary artery disease but can also be used in some patients unable to undergo cardiac MRI to assess arrhythmogenic right ventricular dysplasia. Both 18-F-fluoro-2-deoxyglucose positron emission tomography and delayed contrast-enhanced MRI can be used to assess for cardiac sarcoidosis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.