Regularly ranked as the busiest or the second busiest library in the United States, the King County Library System (KCLS) in Washington annually processes 22 million checkouts and records more than 84 million visits to its catalog. It’s enough to strain any integrated library system (ILS), and a few years ago, IT services director Jed Moffitt decided that, owing to this volume and the need to add proprietary features to its system, there simply wasn’t a commercial ILS on the market that could meet the library’s unique requirements. He famously coauthored an Institute of Museum and Library Services grant of $1 million that enabled KCLS to experiment with, and then migrate to, the open source Evergreen ILS while developing a peer-to-peer support model to help other libraries and consortia that were interested in doing the same. Moffitt admits that there have been growing pains during the past three years. But he still maintains that commercial ILS vendors simply aren’t organized to do the type of development work that KCLS needs.