Background: early iconography of Parkinson's disease, Christopher G. Goetz. Clinical aspects: epidemiology of Parkinsonism, Ali H. Rajput, Alex Rajput, and Michele Rajput; differential diagnosis of Parkinsonism, Kapil D. Sethi; pathophysiology and clinical assessment of Parkinsonian symptoms and signs, Joseph Jankovic; nonmotor symptoms of Parkinson's disease, Richard B. Dewey, Jr; neuropsychological aspects of Parkinson's disease and Parkinsonian syndromes, Alexander I. Troster and Steven Paul Woods; treatment of mental changes, Jorge Juncos; neuroimaging in Parkinson's disease, Kenneth Marek, Danna Jennings, and John Seibyl. Pathology and neurochemistry: neuropathology of Parkinsonism, Dennis W. Dickson; neurochemistry, Jayaraman Rao; neurophysiology/circuitry, Erwin Montgomery; animal models of Parkinson's disease and related disorders, Giselle M. Petzinger and Michael W. Jakowec; dopamine receptor diversity - anatomy, function, and relevance to Parkinson's Disease, Deborah C. Mash. Aetiology: genetics, Zbigniew K. Wszolek and Matthew Farrer; environmental risk factors for Parkinson's disease, Jay M. Gorell and Benjamin A. Rybicki. Medications: amantadine and anticholinergics, Joseph S. Chung, Allan D. Wu, and Mark D. Lew; levodopa, Anthony J. Santiago and Stewart A. Factor; dopamine agonists, Mark A. Stacy; monoamine oxidase inhibitors in Parkinson's disease, Daryl Victor and Cheryl Waters; catechol-o methyltransferase in Parkinson's disease, Ronald F. Pfeiffer; investigational pharmacological treatments for Parkinson's disease, William Ondo. Surgical therapy: lesion surgeries, Michael Samuel and Anthony E. Lang; deep brain stimulation in Parkinson's disease, Rajesh Pahwa and Kelly E. Lyons; neural transplantation in Parkinson's disease, Elmyra V. Encarcion and Robert A. Hauser. Other forms of treatment: Parkinson's disease symptom management - an interdisciplinary approach, Ruth A. Hagestuen, Rosemary L. Wichmann, and Marjorie L. Johnson.