Roughly 95% of public libraries in the United States use the Dewey Decimal System to organize their collections, and it remains the gold standard in library classification systems, but some libraries are beginning to take cues from bookstores--the big chains in particular. While it is not the first public library in the country to drop the Dewey Decimal System, the Maricopa County Library District in Arizona got a lot of attention in library circles when its Perry Branch Library opened this month with its entire 24,000-item collection organized alphabetically by author under 50-plus subject headings used by the Book Industry Study Group . (Fifty may seem like a lot of subject headings if you don't know that the Dewey Decimal System classifies all items using 10 main classes, 100 divisions, and 1000 sections.) Adult Services Coordinator for the Maricopa County Library District, Marshall Shore, describes the layout of the new Perry Branch Library as well as the rationale behind its cataloging system here .