More than a quarter century has passed since the initial descriptions of tardive dyskinesia (Schonecker, 1957; Sigwald et aI., 1959). The earliest epidemiologic study of this disorder was carried out in Roskilde, Denmark, by Uhrbrand and Faurbye (1960); the term tardive dyskinesia was first used a few years later in a subsequent paper (Faurbye et aI., 1964). Despite 25 years of intensive investiga- tive scrutiny, the syndrome persists, and approaches to its prevention and treat- ment continue to have limited efficacy. It is thus fitting to evaluate what has already been learned and consider future directions for research. . Tardive dyskinesia is generally dermed as an involuntary movement disorder, mainly involving the mouth, which attends long-term neuroleptic exposure. Beyond these simple facts, however, there has been relatively little consensus about this disorder. A desire to address the controversies associated with tardive dyskinesia prompted the organization of an international symposium at Kolle- kolle, just outside Copenhagen. This publication comprises all 26 presentations.