These international clinical practice guidelines were developed with detailed input from 29 invited international consultants, who provided content as well as detailed feedback on draft versions. The final draft of the guidelines was ratified by the Executive of the International Early Psychosis Association and presented and formally endorsed at the Third International Conference on Early Psychosis held in Copenhagen, September 2002. They have been revised slightly to include medications that were not available in 2002, although a fully comprehensive process of update has not yet been conducted. The final version is published in this Supplement with the aim of encouraging further discussion as well as providing practical guidance to clinicians and researchers. A second edition is planned for publication in 2008.