A comprehensive review of what is known not only about the cause and treatment of atypical parksonian disorders, but also the issues that clinicians, researchers, patients, and caregivers face in dealing with them. The authors cover the basic science (history, epidemiology, genetics, pathology, nosology, computer modeling, and animal models), detailed clinical and laboratory assessments, and available diagnostic tools, including neuropsychiatric, neurologic, neuropsychologic, speech, electrophysiologic, and imaging evaluations. Current and future therapeutic approaches are also detailed, along with extensive discussions about future research directions.