Concussion associated with sport is a common occurrence with an estimated 1.6 to 3.8 million sports-related concussions yearly in the United States. The sideline assessment of concussion focuses on four areas: cognitive ability, balance, associated symptoms, and visual tracking. Tools available on the sideline to assist in the diagnosis of concussion are discussed in this article. Some of these tools are validated and reliable and some are developing and have yet to be proven to be sensitive enough for routine use. These tools along with a thorough history and physical examination enable a sideline physician to accurately diagnose concussion.