The authors discuss aspects of the decision-making process for including "new" diagnostic categories in DSM-IV. They detail the different kinds of new categories proposed for inclusion in DSM-IV and discuss the risks and benefits of incorporating them. The authors comment on whether new diagnostic categories should be included in official nosologies as a stimulus for research or as a culmination of research. They also highlight problems with "sunsetting" diagnoses. The criteria for change in DSM-IV--a way to deal with the expanding array of proposals for additional diagnostic entities--are discussed. The authors also offer a series of specific examples of the different kinds of new categories being considered for inclusion in DSM-IV.