Continuity of operations at Department of Defense (DOD) installations is vital to supporting the departments missions, and the disruption of utility services -- such as electricity and potable water, among others -- can threaten this support. DOD installations have experienced utility disruptions resulting in operational and fiscal impacts due to hazards such as mechanical failure and extreme weather. Threats, such as cyberattacks, also have the potential to cause disruptions. This book addresses whether threats and hazards have caused utility disruptions on DOD installations and, if so, what impacts they have had; the extent to which DODs collection and reporting on utility disruptions is comprehensive and accurate; and the extent to which DOD has taken actions and developed and implemented guidance to mitigate risks to operations at its installations in the event of utility disruption. Moreover, DOD relies overwhelmingly on commercial electrical power grids for secure, uninterrupted electrical power supplies to support its critical assets. This book also examines the extent to which DODs most critical assets are vulnerable to disruptions in electrical power supplies and the extent to which DOD -- both within and outside of the Defense Critical Infrastructure Program -- has attempted to assure the availability of electrical power supplies to its most critical assets.