Collection development in a school library is different from how collections are cultivated in public or private libraries in that school librarians have to be accountable to school boards, teachers, curriculum standards, parents, and students all at the same time. Our user base may be smaller, but the needs that must be filled are numerous; for example, making sure that a class of fifteen students each has a book on an animal of their choice that each student can read, oh, and by the way, your student's have reading levels span from preschool to an average ninth grader. This isn't to whine or complain, the challenge of suiting the needs and wants of all of the previously mentioned groups is one of the best parts of this job as far as I'm concerned, but it still remains a challenge.
No librarian, regardless of how good they are, can possibly fill and fit every request and need by every library user, but striving to fill and fit as much as we can along with trying to guide patrons to other materials that resemble the things they want is one of the many parts of being a librarian and who knows, it may be the way you discover your new favorite book?