Croup refers to airway inflammation and edema leading to obstruction of the larynx, trachea, and bronchi. Croup is the most common cause of acute airway obstruction in young children. It is characterized by the onset of low-grade fever, barky cough, stridor, hoarseness, and respiratory distress. Croup is typically caused by a viral infection (viral croup) but can occur suddenly without a viral prodrome (spasmodic croup). Recurrent croup is defined as two or more episodes per year. Recurrent croup should be considered a symptom of an underlying structural or inflammatory airway abnormality and should prompt a work-up for the underlying cause.