Thymomas are relatively uncommon. Nevertheless, an accumulation of studies (mostly retrospective, single-institution series) have made it important to approach this disease in a knowledgeable, evidence-based fashion. This begins with the approach to evaluation of a patient with an anterior mediastinal mass, in whom a reliable clinical diagnosis is usually possible in experienced centers. Surgical resection is the mainstay of treatment, and every effort must be made to achieve a complete resection.