Children with asthma frequently receive care in the emergency department (ED). The factors associated with presentation to the ED are complex and must be considered when developing a treatment plan and disposition. The diagnosis and assessment must be rapid and focused, and treatment must be initiated promptly. Objective measures should be used where possible to assess the response to therapy and determine readiness for discharge. This Article reviews the essential components of diagnosis, assessment, and treatment of pediatric asthma in the ED, and it reviews the key elements of discharge planning.