The principal chemical deterioration mechanisms for photographic materials are reviewed, dividing the subject into problems which affect the generic components of a photographic object: the final image material (silver and organic dyes), binder layer (gelatin, albumen, or collodion), and support (metal, glass, paper, and plastic). Concerning silver images, oxidation and improper processing are the most important deterioration mechanisms, while for dyes photooxidation and thermal instability are paramount. Protein binder materials are suspceptible to physical damage and fungus growth. Deterioration of cellulosic plastic film supports due to acid-catalyzed hydrolysis is extensively discussed. The importance of controlled relative humidity and temperature in photographic storage is emphasized. Temperature is of highest importance with chromogenic color materials, while RH and contaminants are critical in the rpeservation of silver images.