Thyroid nodules are quite prevalent in the United States, and are often discovered as incidental findings on a physical exam, or through radiographic studies. The clinical importance of thyroid nodules rests with the need to exclude ones that may harbor malignancy, or in a patient with hyperthyroidism, to identify if the nodule is the autonomous source of excessive thyroid hormone production. This is usually accomplished by obtaining a detailed history, physical exam, and thyroid function tests, in addition to a thyroid and neck ultrasound. The information obtained will then direct subsequent evaluation, including the need for fine-needle aspiration (FNA) biopsy assessment. The management of the nodule is dictated by these findings and subsequent behavior. This chapter encompasses the clinical description of thyroid nodules, in addition to diagnosis and management.