This book reviews neurophysiological biomarkers in neuropsychiatric disorders from the viewpoint of the 21st Century Cures Act, which encourages the use of biomarkers for a variety of purposes during drug development. It covers both traditional etiologic uses of biomarkers and the more recent Biomarkers, EndpointS, and other Tools (BEST) classification scheme used by the FDA, which permits biomarkers for purposes of susceptibility, diagnosis, monitoring, prognosis, pharmacodynamics/response, and safety. The first section of the book describes potential uses of neurophysiologic biomarkers. Subsequent sections focus on a wide range of conditions, including schizophrenia, autism spectrum disorder, Parkinson's disease, and depression, as well as cross-diagnostic and translational uses, including monkey and rodent analogs. The purpose of the book is to help clinicians understand how neurophysiological biomarkers may be used to understand and manage clinical conditions; to help researchers to understand how biomarkers may be used translationally to test specific theories; and to help pharma investigators to understand how biomarkers can be used to accelerate treatment development.