To assume the role of technology leaders and information literacy specialists in their schools, librarians need access to the most current information. And, they do this by helping each other. There are many definitions, but professional learning networks (PLNs) involve sharing work-related ideas with a network of colleagues via various digital communications (and even face-to-face) for the betterment of one's professional practice. A robust PLN employs different technologies to network around different content types. Heavy-hitters include Twitter for micro-blogging (follow the #tlchat hashtag); Google Reader for aggregating blog feeds; FourSquare for geolocation to follow colleagues at conference or other sites; professional networking sites, including FaceBook (join professional groups), Google+, and Edmodo (password-protected); and specialty sites, such as Diigo (bookmark sharing), Goodreads, Shelfari, and LibraryThing (book info sharing); or SlideShare (presentations) and Scribd (documents). This article presents five reasons why school librarians need robust PLNs and offers some advice for effective participation in a PLN.