BK - Here's what my library's material selection policy says about young adult literature:
"YOUNG ADULT COLLECTION
Adolescence is the transitional age from childhood to maturity and an experimental stage during which young people investigate a wide variety of interests. Young adults may use a wider range of library materials than any other age group. While the entire collection is available to the young adult, the library recognizes that certain materials have a special appeal or message for this group. Some items are purchased only for the young adult collection. However, many items found here are duplicated in the children's collection, in the adult collection, or in both.
The young adult collection includes recreational reading, including fiction and non-fiction, paperbacks, magazines, and graphic novels (comic book format), particularly appropriate to adolescents ages 12 through 18. It is not intended to be a comprehensive collection serving all the needs and interests of young adults, nor is it the library's intention that young adults should be confined to the use of this material.
Materials are selected for this collection to broaden the horizons of young adults and help them to cope with the problems of adolescence. To fulfill these needs, the collection will inevitably include materials on controversial topics...."