Asthma is a chronic respiratory condition characterized by recurrent episodes of reversible lower airways obstruction which occur due to inflammation and smooth muscle constriction of the small to medium-sized airways. Children typically present during exacerbations with some combination of dyspnea, tachypnea, increased work of breathing, wheezing, and cough. While nearly half of all children will have bronchospasm with viral infections in the first years of life, only a fraction will go on to develop asthma. The diagnosis of asthma is typically made after a child has experienced multiple episodes with responsiveness to steroids or inhaled bronchodilators. Exacerbations are typically triggered by viral respiratory illnesses among infants and toddlers, and increasingly by allergens or other environmental exposures later in childhood. Asthma is a clinical syndrome, and there is no single gold standard test that can be used to rule it out, or to establish its presence with complete certainty. Diagnosis of asthma in children presents unique challenges. Histories may be somewhat ambiguous as children are often unable to report symptoms reliably. Wheezing, prolonged expiratory phase, or decreased breath sounds may be heard on lung auscultation during an exacerbation, but children with asthma may have a normal exam in the absence of ongoing bronchospasm. Pulmonary function testing may be used to support the diagnosis, but many children are unable to produce reliable results. Treatment of asthma in children largely mirrors approaches used in adults. Inhaled corticosteroids are the mainstay of controller therapy, while other classes of medications, including biologic therapies, may also be employed. Ensuring adherence to treatment plans and use of proper technique with inhaled medications present particular challenges in the young. In general, children have fewer comorbidities than adults, but chronic conditions such as obesity are increasingly common in children and adolescents. The presence of comorbid conditions can complicate asthma diagnosis and management.