Two NSF awards (NSF EAR-0632516 and NSF EAR-0819857) have provided funding in two rounds to develop 11 seed sites in the continental U.S. and Puerto Rico. Research at eight sites was funded by the first award. With the award of NSF EAR-0819857, three new seed sites were added with new activities funded at one of the existing sites. The 11 sites offer researchers opportunities to examine the interconnectedness of Critical Zone processes in different lithologies, climates and topographies. One of the initial seed sites, the Susquehanna Shale Hills Observatory, has since become an NSF-funded Critical Zone Observatory (Shale Hills CZO NSF-0725019).