Remodeling reflects the structural and functional deterioration that occurs in heart failure. Indices of remodeling constitute an important marker of the severity of heart failure, and reverse remodeling is an accepted goal in the treatment of heart failure. Cardiac resynchronization therapy (CRT) has been shown to reverse the remodeling process by improving ventricular size, shape, and mass and reducing mitral regurgitation in the short and long term. Diastolic function, right ventricular size, and atria exhibit reverse remodeling. Trials of medical therapy for heart failure strongly link remodeling indices with outcomes, and emerging data suggest that remodeling indices may be among the most accurate predictors of long-term morbidity and mortality in heart failure patients with CRT devices. This review discusses remodeling and focuses on the evidence for CRT-induced reverse remodeling.