Potential candidates for lung volume reduction surgery should undergo extensive evaluation and preparation to minimize perioperative risks and optimize surgical outcomes. Initial screening includes spirometry, diffusion capacity, lung volumes by body plethysmography, and high-resolution computerized tomography scanning. Patients who have been successfully screened must complete a preoperative pulmonary rehabilitation program of 6-10 weeks duration. During the pulmonary rehabilitation program, medical therapy should be maximized. Postrehabilitation studies include cardiopulmonary exercise testing, arterial blood gas analysis, oxygen titration, six-minute walk, and cardiac testing. The evaluation process aims at defining the severity and distribution of emphysema and attempts to eliminate those who do not meet criteria outlined by the National Emphysema Treatment Trial. Optimal candidates have upper-lobe-predominant emphysema and acceptable operative risks.