The sideline assessment of concussions is a complex multisystem assessment to detect whether an athlete shows signs or symptoms of concussion and should be removed from practice or competition to prevent greater neurologic compromise. Sideline concussion assessments are challenging given some of the environmental conditions, substitution rules of some sports, the possibility of athletes underreporting symptoms, and the difficulties of defining a concussion. The SCAT is the standard of care and is augmented with other procedures to enhance sensitivity and specificity. Serial assessments acutely are important to detect any evolving neurologic emergencies. This article provides a detailed review of the procedures in performing a sideline concussion assessment.