In order to address the needs of tomorrow s National Airspace System (NAS) users, the Federal Government is implementing the Next Generation Air Transportation System (NextGen). The success of NextGen will rely, in part, on the ability to provide the right information to the users that need it, when they need it. NextGen is implementing a net-centric environment to ensure that relevant, accurate, timely, and well-understood information is available to any authorized consumer and irrelevant information is filtered out. The ability to precisely direct information to users is accomplished through the use of ontologies and semantic technologies. An ontology is a set of terms, arranged hierarchically, that represent the real world objects and processes within a given domain (e.g., weather, surveillance, and safety) that has been encoded in a formal, machine-readable language. Within the context of information sharing, the ontology is used to more precisely define the meaning of an organization s data elements and attributes. The ontology provides the basis for a semantic search capability that goes well beyond simple keyword searches to searches that take into consideration the meanings of the search term (e.g. a search for dog should find items that contain the word canine since they mean the same thing). Ontologies are a key to effective information sharing across multiple communities with varying terminologies and operational needs. This document describes the approach used by the Joint Planning and Development Office (JPDO) Net-Centric Operations Division (NCOD) in sponsoring the development of ontologies and encouraging ontology implementation in support of Net-Centric information exchanges. This approach uses small, agile development teams, called Community of Interest (COI) Engagement Teams, to create an inter-organizational environment that is efficient, sustainable, and extensible.