−−−−This paper describes the field trial experience on the control and coordination of an interactive videoconferencing system. The system employs ATM and Internet networks to realize the continuous presence and the conference control and management, respectively. Four control and management functions are designed to closely emulate interactive videoconferences. Unlike middleware approaches, we developed a service-specific, programmable control and management platform for multimedia applications. Based on the platform, a centralized architecture is employed to realize the conference control and management in a prototype system. Running the prototype system in Taiwan ATM/Internet networks, we observed diverse aspects of the system behavior. The control and coordination behavior naturally depends on the specified service and designated architecture and noticeably reveals the characteristics of the underlying Internet/ATM networks.