Check out these resources created by the AASL/ALSC/YALSA Interdivisional Committee on School/Public Library Cooperation.
Public Library & School Library Collaboration Toolkit
Both public and school libraries are community centers at heart, with the same goal: to provide a safe, welcoming environment for all patrons and access to information in a variety of formats. When public and school librarians and library workers engage in collaboration, community members reap the benefits. This toolkit includes context and suggestions for creating partnerships of all sizes.
Collaboration Toolkit - Print Ready (PDF - 1 MB)
Collaboration Toolkit - Screen Friendly (PDF - 745 KB)
List highlighting past successful partnerships between school & public libraries.