It is important to carefully evaluate self-reported symptoms in athletes with known or suspected concussions. This article presents data on the psychometric and clinical properties of a commonly used concussion symptom inventory-the Post-Concussion Scale. Normative and psychometric data are presented for large samples of young men (N = 1,391) and young women (N = 355). In addition, data gathered from a concussed sample of athletes (N = 260) seen within 5 days of injury are presented. These groups represent samples of both high school and collegiate athletes. Data from a subsample of 52 concussed athletes seen 3 times post-injury are presented to illustrate symptom reporting patterns during the initial recovery period. General guidelines for the clinical use of the scale are provided.