Here’s a quote from American Association of School Librarians website:
School Library Month (SLM) is the American Association of School Librarians’ (AASL) celebration of school librarians and their programs. Every April school librarians are encouraged to create activities to help their school and local community celebrate the essential role that strong school library programs play in a student’s educational career. The 2010 theme will be “Communities Thrive @ your library.”
You might be interested in The Best Sites To Teach ELL’s About Libraries.