A thyroid nodule detected clinically or incidentally at medical imaging is a common indication for ultrasonography (US) in the adult population. This scenario is less frequently the case in pediatric patients, and the approach to evaluation of thyroid nodules deserves modification in these patients because of the increased probability of malignancy in children, compared with adults. Evaluating a thyroid nodule with US in a systematic way requires familiarity with a number of features that can be assessed and the terms that the radiologist uses in each category. The probability of malignancy is influenced by certain features, and several models have emerged to integrate these details into an overall risk assessment to guide management and biopsy of thyroid nodules. Clinical features of thyroid cancer differ between pediatric and adult patients, and risk factors and certain genetic syndromes portend earlier manifestation of thyroid malignancy. This article provides a review of (a) US features of thyroid nodules with an emphasis on the predictive capacity for malignancy, focused on the pediatric age group when the data exist, (b) clinical information, including risk factors and genetic syndromes pertinent to the pediatric population, and (c) the state of the current literature and controversies in diagnosing and managing pediatric thyroid cancer. ©RSNA, 2017.