The presentation recaps the definition of interoperability and what the benefits might be to the user community, toll operators and system developers. It discusses the level of interoperability that exists today and the future plans for attaining higher levels of interoperability. The proprietary nature of existing systems and laws is discussed. The presentation generally contrasts the U.S. effort to that of other parts of the globe and the potential for international efforts. Several interoperability schemes are discussed in detail including the northeastern U.S. Interagency Group (IAG), the California Title 21 statutory process and the proposed Vehicle Infrastructure Integration (VII) which will be in the 5.8 GHz range.