12 Since 1995, the CEOS Calibration/Validation (Cal/Val) Database has provided the international Earth remote sensing science community with a) a central repository for information on current and planned Calibration/Validation activities and b) a means to foster collaboration on common Cal/Val issues. The Cal/Val Database uses an ORACLE relation database management system to store the data and is accessed via the World Wide Web (WWW) using PERL scripts to search and query the database. The search queries are structured such that users can define any combination of fields, either through selection of valids, or by directly typing the information. All query results are displayed in the text form. The text displays are interactive allowing the user to point and click to access more detailed information. System functionality provides an on-line form of all of the three questionnaires for submitting new information and allows a user with the assigned password to edit archived information for their facility. This functionality allows users to update information, as it becomes available. In 2000, the Cal/Val database was updated through a process of additional surveying of existing and planned Cal/Val capabilities to support the NASA's Earth Science Enterprise (ESE) and other international Earth observing missions. A set of three updated questionnaires was prepared: one for calibration laboratories, one for test sites, and one for field instruments. The information requested included: a description of the facility, instruments available, instrument characteristics, types of measurements performed, programs/projects that have used the facility, etc. These questionnaires with cover letter were mailed to over 250 research groups that included CEOS members and facilities within the USA. The information collected from worldwide facilities was used to construct and update this on-line database for use not only by the CEOS members, but also the broader international Earth science community.