The authors discuss the development of a testbed, called the distributed simulation and prototyping testbed (DSPT), to model variable-connectivity radio networks. The DSPT constitutes a software environment in which distributed simulation and prototyping models of radio communication and command and control systems can easily be built. The environment consists of four separate software packages: communication simulation, communication monitor, scenario update/controller, and prototype node. These four packages work together to form a single distributed simulation and prototyping facility for communication network studies. They relieve the user from the need to consider many of the details that must be handled to implement a distributed testbed. Each package is easily extensible and can be tailored to specific networks, scenarios, monitor views, and prototyping needs.>