The IOOS Observation Registry is a database that defines the operational status and distribution of in situ ocean observation activity among the non federal participants in IOOS. Its primary purpose is to support strategic planning for resource allocation and to facilitate the discovery and utilization of observation data. Its design is based on a distributed network of nodes across the country that expose their resources to the public through web services. Each node is regularly polled for its operational status and compiled into a national view. Metadata will be 'machine harvested' and/or provided manually by IOOS partners through a web-based form process. The metadata format of this system will adhere to GML format standards. The Observation Catalog project has been initated by the National Marine Sanctuary Program's SIMoN team and is being developed under guidance by MMI, NOAA's Coastal Services Center, members of the IOOS DMAC Committee, and the Central and Northern California Ocean Observing System (CeNCOOS).