The Fourth International Obsessive Compulsive Disorder Conference (IOCDC) was held February 10–12, 2000, on the beautiful island of St. Thomas. The IOCDC is an annual meeting which brings together the world's leading experts in obsessive-compulsive disorder (OCD) and related disorders in a small workshop setting to present recent research advances, discuss gaps in our current knowledge, and plan or international approaches that address these knowledge gaps. The IOCDC meetings have been held on islands on both sides of the Atlantic—Capri, Guadeloupe, Madeira, and now St. Thomas.

The International Organizing Committee consists of Eric Hollander, MD (USA), Joseph Zohar, MD (Israel), and Donatella Marazziti, MD (Italy). The proceedings are generously supported by an unrestricted educational grant from Solvay Pharmaceuticals Inc. and Solvay Pharmaceuticals, and we would like to acknowledge the very important contributions of Chantal Vekens and Mary Blangiardo of Solvay. Also, an mportant part of the success of these meetings stems from the very active role of the chairpersons and cochairpersons of the workshops who lead the discussions, who synthesize the future directions and prepare the manuscripts that result from these discussions that appear in this academic supplement.

The meeting led off with a state-of-the-art plenary address by Mark George, MD (USA), describing how new methods of brain stimulation are improving research and therapy in OCD and promise to revolutionize neuropsychiatric research and herapy over the next decade. He describes how transcranial magnetic stimulation (TMS) is used to test the circuits in OCD and test electrophysiologic evaluations of cortical inhibition n OCD. Newer techniques that are less invasive than ablative surgery and appear promising in OCD therapy include vagus nerve stimulation and deep brain stimulation.