This project report defines network robustness and discusses capability indicators that could be used to analyze network robustness. Growing dependence on telecommunication networks and recent network outages have focused attention on network robustness. The National Communications System (NCS), a confederation of 23 Federal departments and agencies, has been concerned with network robustness since its formation in 1963. The NCS is developing and implementing systems and services that enhance the capability of the public switched networks to support critical Government communication requirements during times of crisis or emergency. Quantitative indicators of network robustness are needed to analyze the benefits of these enhancements. This project proposes a set of candidate capability indicators that could be used by the NCS in future analyses of the public switched networks with and without network enhancements.