Satellites are emerging as an ideal medium for a host of new global communication services. NASA s Advanced Communications Technology Satellite has provided an in-orbit test bed for pioneering, evaluating, and validating some of the cutting edge communication technology needed to implement these new services for the twenty-first century. The development and in-orbit testing of ACTS has helped to herald a new advance for the role of satellites in the information revolution. ACTS pioneered four key technology breakthroughs: on-board circuit switching and processing, dynamic hopping spot beams, very wideband transponders, and use of the Ka-band portion of the frequency spectrum. The advanced switching technologies provided ACTS users with bit rates on-demand. The multiple spot beam technology permitted a high degree of frequency re-use and small terminals for direct user-to-user (mesh) interconnectivity. With a high degree of frequency reuse, the capacity for a single satellite in orbit can be much greater, with a resultant reduction in service cost. Trials with the ACTS test network have validated on-demand, high-bandwidth, integrated voice, video, and data applications that can potentially be provided at a service price that is competitive with terrestrial communications. In today s deregulated environment, the reduction in service cost is crucial if satellites are to remain competitive.