The purpose of the thesaurus is to ease the task of describing the photographic processes, forms, genres, and trade names found in the collections of the Smithsonian Institution. The thesaurus was created as an adjunct to the Photo Survey Project, which is a complete survey of photographic collections in the Smithsonian Institution. It will assist in the selection of descriptive vocabulary, serve as an authority file for the project data base, and serve as a portion of the indexing structure for the master guide to Smithsonian photographic collections. In addition, it will serve as a field guide to photographic processes by assisting staff in photographic process identification during the survey process. This is a draft thesaurus; comments and corrections are solicited.