A concussion is a mild traumatic brain injury that is a clinical diagnosis, relying on a combination of signs, symptoms and objective findings. Understanding available diagnostic tests for the sideline and office setting is critical for primary care clinicians. Each concussion and each patient are unique; therefore having a wide range of diagnostic tests is necessary to detect deficits in different domains. Primary care clinicians and qualified healthcare professionals evaluating concussions can utilize this information to develop their armamentarium for concussion diagnosis and management. This chapter features a case-based approach to cover a wide range of diagnostic tests encompassing symptom scores, Standardized Assessment of Concussion (SAC), balance testing, vestibular ocular motor screen (VOMS), Sports Concussion Assessment Tool 6 (SCAT6), and Child SCAT 6, Sports Concussion Office Assessment Tool (SCOAT6), orthostatic vital signs, and Buffalo Treadmill Test. After an introduction to these diagnostic tests, the evidence supporting their use is presented.