"The Thesaurus of Psychological Index Terms® is the controlled vocabulary used by the American Psychological Association's (APA) professional indexers to index all of APA's databases: PsycINFO®, PsycARTICLES®, PsycBOOKS®, PsycEXTRA®, and PsycCRITIQUES®. With the wide variety of concepts and vocabulary used in the psychological literature, search and retrieval about specific concepts is virtually impossible without the controlled vocabulary of the Thesaurus. It provides a way of structuring the subject matter in a way that is consistent among users. The Thesaurus of Psychological Index Terms, first published in 1974, has an influential role in research because it reflects the most current trends found in the behavioral and social science literature. The Thesaurus can help authenticate the use of terms as they become accepted nomenclature. " --Editor; from Preface, page v.