One of the most exciting developments in the intelligent transportation systems (ITS) industry—one that holds so much promise for the future—is the National Transportation Communications for ITS Protocols (NTCIP). NTCIP will help lead the way to achieve a cost-effective deployment and management of ITS applications. It will also influence the design and manufacturing process and should cause changes in the way system integrators do their work. The resulting interoperability of core functionality between transportation devices will be an enabling service for ITS deployment. Developmental efforts, the implications of NTCIP, and the resulting interoperability for transportation applications are reported. The framework of the NTCIP is described and device level interoperability is discussed. NTCIP makes an effort to fulfill the initial needs for interoperable and interchangeable field devices. Current developments of the NTCIP effort are described and interoperability features are identified.