OBJECTIVES To examine the incidence, duration, and clinical course of individual post-concussive symptoms in patients presenting to a pediatric emergency department (ED) with a concussion. METHODS We conducted secondary analysis of a prospective cohort study of patients 11 to 22 years old presenting to the ED of a children's hospital with an acute concussion. The main outcome measure was duration of symptoms, assessed by the Rivermead Post-Concussion Symptoms Questionnaire (RPSQ). Patients initially completed a questionnaire describing mechanism of injury, associated symptoms, past medical history, and the RPSQ, then were serially administered the RPSQ for 3 months after the concussion or until all symptoms resolved. RESULTS Headache, fatigue, dizziness, and taking longer to think were the most common symptoms encountered at presentation, whereas sleep disturbance, frustration, forgetfulness, and fatigue were the symptoms most likely to develop during the follow-up period that had not initially been present. Median duration of symptoms was the longest for irritability (16 days), sleep disturbance (16 days), frustration (14 days), and poor concentration (14 days), whereas nausea, depression, dizziness, and double-vision abated most quickly. One month after injury, nearly a quarter of children still complained of headache, >20% suffered from fatigue, and nearly 20% reported taking longer to think. CONCLUSIONS Among patients presenting to a pediatric ED after a concussion, physical symptoms such as headache predominate immediately after the injury, emotional symptoms tend to develop later in the recovery period, and cognitive symptoms may be present throughout.